A global motion estimation technology based on MPEG was put forward. First, a four parameter model, which is used to describe the global motion yielded by camera motion, was proposed. Then these parameters were obtained by using an algorithm which is based on block matching, and the global motion could be compensated by these four parameters. Since the motion vectors include the information of the optimum match blocking, these information can be used without completely decoding the MPEG video sequence. The experiment shows that the algorithm is fast, and feint motion field can be excluded by global motion compensation.