understanding the characteristics of user activities make sense to various application designs, and consequently has impact on business benefit directly. In this paper, we present a study of a peer to peer (P2P) live streaming system based on measurement. We classify those channels into three types and study the statistical characteristics on user behaviors, such as user arriving and leaving, especially we conduct an in-depth analysis of their relations with program time point and time duration. We observe that users behave differently not only inside different type of channels but also different programs. We find that 1) peers watching time duration has no necessary relationship with peer interest; 2) peers watching time duration is enormously affected by program arrangement; 3) peers behavior is substantially active in the first 10min of a program. We also come up with a heuristic model about the number of online peers during a program and the watching time duration of one online user. Our study can be used as a reference for arranging the program resources and channel resources so as to attract more viewers to stay longer in the streaming system. This has important implications on not only the design and development of P2P streaming system and IPTV systems, but also the existing general TV system.