diff --git a/AstroLib/Include/AsAttitudeParam_2023.h b/AstroLib/Include/AsAttitudeParam_2023.h
index c714c38fa186509133fb5f51120ee7b55e46966b..fce88475bfb2984b396694f5df6b43aa234a404b 100644
--- a/AstroLib/Include/AsAttitudeParam_2023.h
+++ b/AstroLib/Include/AsAttitudeParam_2023.h
@@ -74,6 +74,17 @@ void	AsMtxToEuler313(const CMatrix<double>& mtx, CEuler& euler);
 ///***********************************************************************
 void	AsMtxToEuler312(const CMatrix<double>& mtx, CEuler& euler);
 
+///***********************************************************************
+/// 方向余弦矩阵转为121转序Euler角
+/// @Author	Zhang Xuaying
+/// @Date	2023.04.01
+/// @Input  
+/// @Param	mtx  		方向余弦矩阵
+/// @Output	
+/// @Param	euler		欧拉角(rad)
+///***********************************************************************
+void	AsMtxToEuler121(const CMatrix<double>& mtx, CEuler& euler);
+
 ///******************************************************
 /// 根据转序和坐标转移矩阵计算Euler角，转序为2-3-1
 /// @author Sun Fengyan