Tencent QQ is the most popular instant message communication tool in China, which has more than 780 million users and thus generates huge traffic on the Internet. However, due to its proprietary protocol and encryption mechanism, it is very hard to identify QQ traffic at a fine-grained flow level. To solve this issue, this paper proposes a novel identification method, which uses a Payload and Behavior Combination (PBC) technology. PBC combines the packet payload characteristics with behavior characteristics existing in the QQ communication process. The experimental results show that PBC has a good identification accuracy in dealing with QQ traffic.