In order to study the amount of bandwidth resource loss caused by flash P2P technique, its influence on network load and its maintenance cost, the characteristic of Internet traffic of flash P2P is studied. On the basis of analysis of features of Real time media flow protocol (RTMFP), the traffic of flash P2P can be identified from the Internet traffic. By extraction and analysis of the traffic of the three largest online video content providers in China (Youku, Iqyi and Sohu Video) and the calculation of probability distribution of the traffic, it is found that the transmission time of flash P2P traffic and the transmission time interval obeys the heavy-tailed distribution. This accounts for the self-similarity of the flash P2P traffic. To better explain the phenomenon, the long-range dependent model is established based on the current traffic. By the established mathematical model, it is strictly proved that flash P2P traffic has self-similar characteristic.