In intelligent transport system, it is very important to precisely segment motion object from complex scene. Background difference and frame difference are two classic motion object extraction algorithms. If there are shadows associated to moving objects, both of the methods can’t extract moving object precisely. With this problem, this paper proposes a motion object extraction algorithm based on active contour model. The following steps are performed in the proposed algorithm. Firstly, moving areas involving shadows are segmented with classical background difference algorithm. Secondly, perform shadow detection and coarsely removal, then using grid method to extract initial contours. Finally, use active contour model approach to the contour of the real object by iteratively tuning the parameter of the model. Experiments show the algorithm can remove the shadow and keep the integrity of moving object.