To accrue more profits in market competitions, the power producers sometimes would adopt the collusion bidding strategy to force up prices. The paper discusses the collusion bidding behavior of the power producers, which is based on the actual running data of trans-provincial electric power market of the East China Power Grid. Firstly, the probability analysis based on the bidding data of the monthly producers is used to confirm whether it is a collusion one. On this foundation, based on the basic principles of the cooperative game, we analyze the internal mechanisms of the collusion bidding, and show the relationship between market rules and this behavior. Furthermore, several possible strategies are proposed to inhibit it. Both the theoretical analysis and the market practice show the effectiveness of the proposed strategies.