Movie-on-demand services often cost a lot of storage and transport bandwidth. To increase the efficiency of these resources is the key issue of deploying large scale movie-on-demand network. In this paper, the sequence of movies accessed by the subscribers was analyzed. Based on this analysis, a movie-access-model with content updating was built. Then an improved time-window-based content caching algorithm was proposed to solve the problem caused by content updating. And the algorithm was investigated through network simulation. The simulation results show that this algorithm can meet the requirement of content updating.