Abstract: There are two limitations in the traditional CBR MPEG 2 rate control strategy. One is that the encoder does not take full account of the relative complexity of a frame in the target bit number allocation, and the other is that scene changes are not properly dealt with. An improved rate control strategy is proposed for solving these two deficiencies in this paper. First, average encoded pictures complexity computation algorithm is presented, and target bit number can be reasonably adjusted by comparing the complexity of current frame with the average. Second, a scene change detection algorithm is put forward, and the frame target bit number can be adjusted dynamically. The experimental results indicate that the improved rate control algorithm performs better than the TM5 rate control algorithm.