Abstract: To reduce manual intervention and improve the efficiency in facial expression tracking,a new method for 3D facial expression tracking based on normal-preserving is presented in this paper.The new method takes the time-varying face point clouds obtained at video-rate as input,and uses a deformable parametric mesh model to register each point cloud frame so as to track the varying expression.The normal-preserving condition aims to automatically constraint the intra-frame vertex motion in the tracking process.Compared with those existing facial expression tracking methods,the new method does not need manual selection of feature correspondences in each registration,and also does not need the complicated optical flow computation,so it can achieve automatic facial expression tracking with high efficiency.Additionally,when there is large difference between the shape of the parametric mesh and the point cloud,the new method could also get suggested registration result.