diff --git a/src/kf-gins/gi_engine.cpp b/src/kf-gins/gi_engine.cpp
index 2c062db..64fadee 100644
--- a/src/kf-gins/gi_engine.cpp
+++ b/src/kf-gins/gi_engine.cpp
@@ -385,8 +385,11 @@ void GIEngine::EKFUpdate(Eigen::MatrixXd &dz, Eigen::MatrixXd &H, Eigen::MatrixX
     Eigen::MatrixXd I;
     I.resizeLike(Cov_);
     I.setIdentity();
-    I    = I - K * H;
-    dx_  = dx_ + K * dz;
+    I = I - K * H;
+    // 如果每次更新后都进行状态反馈，则更新前dx_一直为0，下式可以简化为：dx_ = K * dz;
+    // if state feedback is performed after every update, dx_ is always zero before the update
+    // the following formula can be simplified as : dx_ = K * dz;
+    dx_  = dx_ + K * (dz - H * dx_);
     Cov_ = I * Cov_ * I.transpose() + K * R * K.transpose();
 }