MPEG standards are playing a more and more important role in many multimedia applications now, and will continue in the future. An effective index model for MPEG-1,2 streams is presented in this paper. Moreover, an algorithm to construct the index for MPEG-1,2 streams is designed, as well as a solution to access any frame in the streams rapidly based on the model. The experimental results have shown the index model can support the ability of postioning a frame in the stream quickly, and it can be applied to access any frame randomly effectively.