The soccer is one of the most cosmopolitan sports, whose fans are found everywhere in the world. So soccer video is in favor with great mass of spectators. In this paper, based on analyzing of soccer video characteristics, a query description model based on basic semantic unit composite Petri-net (BSUCPN) for soccer video is proposed. Firstly a BSU set of soccer video just like the word set in text is defined, Secondly based on the Petri-net model a description model of soccer semantic query is designed, and then some query descriptions by BSUCPN such as goal, attack, corner kick, foul and substitution are given. The experimental results indicate that this model is robust and generic, and that it can be extended to other ball games and sports video.