This paper, Traditional Mean-Shift tracking principle and achieving procedure are analyzed particularly, and through simulation, the shortage of algorithm is pointed out that algorithm with fixed-size tracking window cannot trace a target effectively when scale of moving body changes. Therefore, an improved algorithm is proposed. Based on computing the mutual information between images, the algorithm can adaptively adjust the tracking bandwidth when the scale of moving body is changed, and the problem of traditional Mean-Shift algorithm is solved. The experiment results indicate that the improved algorithm takes on the better tracking performance and better result for moving bodies.