Abstract: P2P-based IPTV (P2P-TV) is one of the Internet applications grown dramatically currently. It is the key to identify P2P-TV video streaming in real-time for managing the P2P-TV traffic and understanding the networking behaviors. Analyzing the architecture, communications processes, message frames and system characteristics of P2P-TV represented by PPLive, a Crawler-based Identifying Video Flows (CIVF) algorithm and a Protocol characteristic-based Identifying Video Flows (PIVF) algorithm identifying video flows in real-time are proposed. CIVF identifies P2P-TV flows based on the peer information, which is obtained from crawler program, while PIVF makes use of the communication sequence and payload characteristic in P2P-TV applications to achieve real-time identification. The results of experiments in Internet environment shows that CIVF algorithm has features such as ease to realize, not high accurateness and long outdated peer information, and PIVF algorithm has features such as high accurateness, fast working and high expansibility.