With the reform toward power market processing, how to decide electricity price becomes a key problem which one power plant have to face. So in this paper, the authors show two ways to the problem, a pricing model by account and a pricing model by economics, then they analyze the cost structure and counting principle of three-electricity price, which is determined by the methods of repayment of capital with interest (RCI pricing), of the operation period (OP pricing) and of marginal cost (MC pricing). Then similarities and differences among these three pricing methods existing in the transitional period are examined by a case in china. The indicate that it is important and inevitable to reform RCI pricing, to popularize OP pricing and to transfer to MC pricing.