diff --git a/docs/en/07-develop/09-udf.md b/docs/en/07-develop/09-udf.md
index 138378e450..d39721de17 100644
--- a/docs/en/07-develop/09-udf.md
+++ b/docs/en/07-develop/09-udf.md
@@ -298,13 +298,53 @@ select max_vol(vol1, vol2, vol3, deviceid) from battery;
 
 </details>
 
+#### Aggregate Function Example 3 Split string and calculate average value [extract_avg](https://github.com/taosdata/TDengine/blob/3.0/tests/script/sh/extract_avg.c)
+
+The `extract_avg` function converts a comma-separated string sequence into a set of numerical values, counts the results of all rows, and calculates the final average. Note when implementing:
+- `interBuf->numOfResult` needs to return 1 or 0 and cannot be used for count.
+- Count can use additional caches, such as the `SumCount` structure.
+- Use `varDataVal` to obtain the string.
+
+Create table:
+
+```shell
+create table scores(ts timestamp, varStr varchar(128));
+```
+
+Create custom function:
+
+```shell
+create aggregate function extract_avg as '/root/udf/libextract_avg.so' outputtype double bufsize 16 language 'C'; 
+```
+
+Use custom function:
+
+```shell
+select extract_avg(valStr) from scores;
+```
+
+Generate `.so` file
+```bash
+gcc -g -O0 -fPIC -shared extract_vag.c -o libextract_avg.so
+```
+
+<details>
+<summary>max_vol.c</summary>
+
+```c
+{{#include tests/script/sh/max_vol.c}}
+```
+
+</details>
+
+
 ## Developing UDFs in Python Language
 
 ### Environment Setup
 
 The specific steps to prepare the environment are as follows:
 
-- Step 1, prepare the Python runtime environment.
+- Step 1, prepare the Python runtime environment. If you compile and install Python locally, be sure to enable the `--enable-shared` option, otherwise the subsequent installation of taospyudf will fail due to failure to generate a shared library.
 - Step 2, install the Python package taospyudf. The command is as follows.
 
     ```shell
diff --git a/docs/zh/07-develop/09-udf.md b/docs/zh/07-develop/09-udf.md
index d0f9c93652..9438df0b1c 100644
--- a/docs/zh/07-develop/09-udf.md
+++ b/docs/zh/07-develop/09-udf.md
@@ -237,7 +237,7 @@ typedef struct SUdfInterBuf {
 
 #### 标量函数示例 [bit_and](https://github.com/taosdata/TDengine/blob/3.0/tests/script/sh/bit_and.c)
 
-bit_add 实现多列的按位与功能。如果只有一列，返回这一列。bit_add 忽略空值。
+bit_and 实现多列的按位与功能。如果只有一列，返回这一列。bit_and 忽略空值。
 
 <details>
 <summary>bit_and.c</summary>
@@ -287,12 +287,46 @@ select max_vol(vol1, vol2, vol3, deviceid) from battery;
 
 </details>
 
+#### 聚合函数示例3 切分字符串求平均值 [extract_avg](https://github.com/taosdata/TDengine/blob/3.0/tests/script/sh/extract_avg.c)
+
+`extract_avg` 函数是将一个逗号分隔的字符串数列转为一组数值，统计所有行的结果，计算最终平均值。实现时需注意:
+- `interBuf->numOfResult` 需要返回 1 或者 0，不能用于 count 计数。
+- count 计数可使用额外的缓存，例如 `SumCount` 结构体。
+- 字符串的获取需使用`varDataVal`。
+
+创建表：
+```bash
+create table scores(ts timestamp, varStr varchar(128));
+```
+创建自定义函数：
+```bash
+create aggregate function extract_avg as '/root/udf/libextract_avg.so' outputtype double bufsize 16 language 'C'; 
+```
+使用自定义函数：
+```bash
+select extract_avg(valStr) from scores;
+```
+
+生成 `.so` 文件
+```bash
+gcc -g -O0 -fPIC -shared extract_vag.c -o libextract_avg.so
+```
+
+<details>
+<summary>extract_avg.c</summary>
+
+```c
+{{#include tests/script/sh/extract_avg.c}}
+```
+
+</details>
+
 ## 用 Python 语言开发 UDF
 
 ### 准备环境
   
 准备环境的具体步骤如下：
-- 第 1 步，准备好 Python 运行环境。
+- 第 1 步，准备好 Python 运行环境。本地编译安装 python 注意打开 `--enable-shared` 选项，不然后续安装 taospyudf 会因无法生成共享库而导致失败。
 - 第 2 步，安装 Python 包 taospyudf。命令如下。
     ```shell
     pip3 install taospyudf
diff --git a/tests/script/sh/extract_avg.c b/tests/script/sh/extract_avg.c
new file mode 100644
index 0000000000..508a73f7eb
--- /dev/null
+++ b/tests/script/sh/extract_avg.c
@@ -0,0 +1,128 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "taos.h"
+#include "taoserror.h"
+#include "taosudf.h"
+
+// Define a structure to store sum and count
+typedef struct {
+    double sum;
+    int count;
+} SumCount;
+
+// initialization function
+DLL_EXPORT int32_t extract_avg_init() {
+    udfTrace("extract_avg_init: Initializing UDF");
+    return TSDB_CODE_SUCCESS;
+}
+
+DLL_EXPORT int32_t extract_avg_start(SUdfInterBuf *interBuf) {
+    int32_t bufLen = sizeof(SumCount);
+    if (interBuf->bufLen < bufLen) {
+        udfError("extract_avg_start: Failed to execute UDF since input buflen:%d < %d", interBuf->bufLen, bufLen);
+        return TSDB_CODE_UDF_INVALID_BUFSIZE;
+      }
+ 
+    // Initialize sum and count
+    SumCount *sumCount = (SumCount *)interBuf->buf;
+    sumCount->sum = 0.0;
+    sumCount->count = 0;
+
+    interBuf->numOfResult = 0;
+
+    udfTrace("extract_avg_start: Initialized sum=0.0, count=0");
+    return TSDB_CODE_SUCCESS;
+}
+
+DLL_EXPORT int32_t extract_avg(SUdfDataBlock *inputBlock, SUdfInterBuf *interBuf, SUdfInterBuf *newInterBuf) {
+    udfTrace("extract_avg: Processing data block with %d rows", inputBlock->numOfRows);
+
+    // Check the number of columns in the input data block
+    if (inputBlock->numOfCols != 1) {
+        udfError("extract_avg: Invalid number of columns. Expected 1, got %d", inputBlock->numOfCols);
+        return TSDB_CODE_UDF_INVALID_INPUT;
+    }
+
+    // Get the input column
+    SUdfColumn *inputCol = inputBlock->udfCols[0];
+
+    if (inputCol->colMeta.type != TSDB_DATA_TYPE_VARCHAR) {
+        udfError("extract_avg: Invalid data type. Expected VARCHAR, got %d", inputCol->colMeta.type);
+        return TSDB_CODE_UDF_INVALID_INPUT;
+    }
+
+    // Read the current sum and count from interBuf
+    SumCount *sumCount = (SumCount *)interBuf->buf;
+    udfTrace("extract_avg: Starting with sum=%f, count=%d", sumCount->sum, sumCount->count);
+
+    for (int i = 0; i < inputBlock->numOfRows; i++) {
+        if (udfColDataIsNull(inputCol, i)) {
+            udfTrace("extract_avg: Skipping NULL value at row %d", i);
+            continue;
+        }
+
+        char *buf = (char *)udfColDataGetData(inputCol, i);
+
+        char data[64];
+        memset(data, 0, 64);
+        memcpy(data, varDataVal(buf), varDataLen(buf));
+
+        udfTrace("extract_avg: Processing row %d, data='%s'", i, data);
+
+        char *rest = data;
+        char *token;
+        while ((token = strtok_r(rest, ",", &rest))) {
+            while (*token == ' ') token++;
+            int tokenLen = strlen(token);
+            while (tokenLen > 0 && token[tokenLen - 1] == ' ') token[--tokenLen] = '\0';
+
+            if (tokenLen == 0) {
+                udfTrace("extract_avg: Empty string encountered at row %d", i);
+                continue;
+            }
+
+            char *endPtr;
+            double value = strtod(token, &endPtr);
+
+            if (endPtr == token || *endPtr != '\0') {
+                udfError("extract_avg: Failed to convert string '%s' to double at row %d", token, i);
+                continue;
+            }
+
+            sumCount->sum += value;
+            sumCount->count++;
+            udfTrace("extract_avg: Updated sum=%f, count=%d", sumCount->sum, sumCount->count);
+        }
+    }
+
+    newInterBuf->bufLen = sizeof(SumCount);
+    newInterBuf->buf = (char *)malloc(newInterBuf->bufLen);
+    if (newInterBuf->buf == NULL) {
+        udfError("extract_avg: Failed to allocate memory for newInterBuf");
+        return TSDB_CODE_UDF_INTERNAL_ERROR;
+    }
+    memcpy(newInterBuf->buf, sumCount, newInterBuf->bufLen);
+    newInterBuf->numOfResult = 0;
+
+    udfTrace("extract_avg: Final sum=%f, count=%d", sumCount->sum, sumCount->count);
+    return TSDB_CODE_SUCCESS;
+}
+
+DLL_EXPORT int32_t extract_avg_finish(SUdfInterBuf *interBuf, SUdfInterBuf *result) {
+    SumCount *sumCount = (SumCount *)interBuf->buf;
+
+    double avg = (sumCount->count > 0) ? (sumCount->sum / sumCount->count) : 0.0;
+
+    *(double *)result->buf = avg;
+    result->bufLen = sizeof(double);
+    result->numOfResult = sumCount->count > 0 ? 1 : 0;
+
+    udfTrace("extract_avg_finish: Final result=%f (sum=%f, count=%d)", avg, sumCount->sum, sumCount->count);
+    return TSDB_CODE_SUCCESS;
+}
+
+DLL_EXPORT int32_t extract_avg_destroy() {
+    udfTrace("extract_avg_destroy: Cleaning up UDF");
+    return TSDB_CODE_SUCCESS;
+}