Abstract: We present a simplification method of 3D mesh sequences, which is an improvement of the traditional mesh simplification method QEM in terms of topological coherence preserving. Firstly, the sum of the least costs of every edge in different frames is computed and regarded as the choosing standard of contracting edges. Then the same edge in minimum-cost in all the frames in a frame sequence is contracted at the same time, which ensures the same topological simplification of these frames. In order to keep more details in important motion features, a weight factor is allotted to the contraction cost of each edge according to the distorted degree of edge length and crease angle among frames. The experimental results show that our method can not only preserve the topological coherence among all frames after simplification, but also delay the simplification of important motion features.