diff --git a/docs/en/12-taos-sql/06-select.md b/docs/en/12-taos-sql/06-select.md
index 786444ad77a4ba8cd3c4729863dfae0a53cef798..c065245827f8e7edbb0297abef4aa9e5de4a45cc 100644
--- a/docs/en/12-taos-sql/06-select.md
+++ b/docs/en/12-taos-sql/06-select.md
@@ -181,6 +181,14 @@ In TDengine, the first column of all tables must be a timestamp. This column is
 select _rowts, max(current) from meters;
 ```
 
+**\_IROWTS**
+
+The \_IROWTS pseudocolumn can only be used with INTERP function. This pseudocolumn can be used to retrieve the corresponding timestamp column associated with the interpolation results.
+
+```sql
+select _irowts, interp(current) from meters range('2020-01-01 10:00:00', '2020-01-01 10:30:00') every(1s) fill(linear);
+```
+
 ## Query Objects
 
 `FROM` can be followed by a number of tables or super tables, or can be followed by a sub-query.
diff --git a/docs/en/12-taos-sql/20-keywords.md b/docs/en/12-taos-sql/20-keywords.md
index f7eb067c960cd9599153a208cd2781b49b090511..4b479b866b77e1e354d20376ccb869755af76d00 100644
--- a/docs/en/12-taos-sql/20-keywords.md
+++ b/docs/en/12-taos-sql/20-keywords.md
@@ -343,6 +343,7 @@ The following list shows all reserved keywords:
 ### \_
 
 - \_C0
+- \_IROWTS
 - \_QDURATION
 - \_QEND
 - \_QSTART
diff --git a/docs/en/12-taos-sql/29-changes.md b/docs/en/12-taos-sql/29-changes.md
index 8532eeac5d599ca2739393c9e38eec52631e407a..78b6d5fc05b9b03e1e8b3af268bc357dfaa401bc 100644
--- a/docs/en/12-taos-sql/29-changes.md
+++ b/docs/en/12-taos-sql/29-changes.md
@@ -11,12 +11,13 @@ description: "This document explains how TDengine SQL has changed in version 3.0
 | 1 | VARCHAR | Added | Alias of BINARY.
 | 2 | TIMESTAMP literal | Added | TIMESTAMP 'timestamp format' syntax now supported.
 | 3 | _ROWTS pseudocolumn | Added | Indicates the primary key. Alias of _C0.
-| 4 | INFORMATION_SCHEMA | Added |	Database for system metadata containing all schema definitions
-| 5 | PERFORMANCE_SCHEMA | Added | Database for system performance information.
-| 6 | Connection queries | Deprecated | Connection queries are no longer supported. The syntax and interfaces are deprecated.
-| 7 | Mixed operations | Enhanced | Mixing scalar and vector operations in queries has been enhanced and is supported in all SELECT clauses.
-| 8 | Tag operations | Added | Tag columns can be used in queries and clauses like data columns.
-| 9 | Timeline clauses and time functions in supertables | Enhanced | When PARTITION BY is not used, data in supertables is merged into a single timeline.
+| 4 | _IROWTS pseudocolumn | Added | Used to retrieve timestamps with INTERP function.
+| 5 | INFORMATION_SCHEMA | Added |	Database for system metadata containing all schema definitions
+| 6 | PERFORMANCE_SCHEMA | Added | Database for system performance information.
+| 7 | Connection queries | Deprecated | Connection queries are no longer supported. The syntax and interfaces are deprecated.
+| 8 | Mixed operations | Enhanced | Mixing scalar and vector operations in queries has been enhanced and is supported in all SELECT clauses.
+| 9 | Tag operations | Added | Tag columns can be used in queries and clauses like data columns.
+| 10 | Timeline clauses and time functions in supertables | Enhanced | When PARTITION BY is not used, data in supertables is merged into a single timeline.
 
 ## SQL Syntax
 
diff --git a/docs/zh/12-taos-sql/06-select.md b/docs/zh/12-taos-sql/06-select.md
index 394e4a99d59aa3a1a59c2cb483bb2eefd71e44db..b3b8ef38873d20acaefa13515ff0d5785c5acc86 100644
--- a/docs/zh/12-taos-sql/06-select.md
+++ b/docs/zh/12-taos-sql/06-select.md
@@ -182,6 +182,14 @@ TDengine 中，所有表的第一列都必须是时间戳类型，且为其主
 select _rowts, max(current) from meters;
 ```
 
+**\_IROWTS**
+
+\_irowts 伪列只能与 interp 函数一起使用，用于返回 interp 函数插值结果对应的时间戳列。
+
+```sql
+select _irowts, interp(current) from meters range('2020-01-01 10:00:00', '2020-01-01 10:30:00') every(1s) fill(linear);
+```
+
 ## 查询对象
 
 FROM 关键字后面可以是若干个表（超级表）列表，也可以是子查询的结果。
diff --git a/docs/zh/12-taos-sql/20-keywords.md b/docs/zh/12-taos-sql/20-keywords.md
index 7530e803db44f49048f02e2ad6980a288c14fa12..8013698fced2f31ca21dfa220066b027e71cb856 100644
--- a/docs/zh/12-taos-sql/20-keywords.md
+++ b/docs/zh/12-taos-sql/20-keywords.md
@@ -344,6 +344,7 @@ description: TDengine 保留关键字的详细列表
 ### \_
 
 - \_C0
+- \_IROWTS
 - \_QDURATION
 - \_QEND
 - \_QSTART
diff --git a/docs/zh/12-taos-sql/29-changes.md b/docs/zh/12-taos-sql/29-changes.md
index e63825045d5ddc26d289af4bbd7fa808719bb99c..7da8e9f331bd1d9c81e9bde441e35b03900422b0 100644
--- a/docs/zh/12-taos-sql/29-changes.md
+++ b/docs/zh/12-taos-sql/29-changes.md
@@ -11,12 +11,13 @@ description: "TDengine 3.0 版本的语法变更说明"
 | 1 | VARCHAR | 新增 | BINARY类型的别名。
 | 2 | TIMESTAMP字面量 | 新增 | 新增支持 TIMESTAMP 'timestamp format' 语法。
 | 3 | _ROWTS伪列 | 新增 | 表示时间戳主键。是_C0伪列的别名。
-| 4 | INFORMATION_SCHEMA | 新增 |	包含各种SCHEMA定义的系统数据库。
-| 5 | PERFORMANCE_SCHEMA | 新增 | 包含运行信息的系统数据库。
-| 6 | 连续查询 | 废除 | 不再支持连续查询。相关的各种语法和接口废除。
-| 7 | 混合运算 | 增强 | 查询中的混合运算（标量运算和矢量运算混合）全面增强，SELECT的各个子句均全面支持符合语法语义的混合运算。
-| 8 | 标签运算 | 新增 |在查询中，标签列可以像普通列一样参与各种运算，用于各种子句。
-| 9 | 时间线子句和时间函数用于超级表查询 | 增强 |没有PARTITION BY时，超级表的数据会被合并成一条时间线。
+| 4 | _IROWTS伪列 | 新增 | 用于返回 interp 函数插值结果对应的时间戳列。
+| 5 | INFORMATION_SCHEMA | 新增 |	包含各种SCHEMA定义的系统数据库。
+| 6 | PERFORMANCE_SCHEMA | 新增 | 包含运行信息的系统数据库。
+| 7 | 连续查询 | 废除 | 不再支持连续查询。相关的各种语法和接口废除。
+| 8 | 混合运算 | 增强 | 查询中的混合运算（标量运算和矢量运算混合）全面增强，SELECT的各个子句均全面支持符合语法语义的混合运算。
+| 9 | 标签运算 | 新增 |在查询中，标签列可以像普通列一样参与各种运算，用于各种子句。
+| 10 | 时间线子句和时间函数用于超级表查询 | 增强 |没有PARTITION BY时，超级表的数据会被合并成一条时间线。
 
 ## SQL 语句变更