With the in-depth development of the direct power purchase by large consumers

the contradiction between the marketization of medium-long term bilateral transactions and the non-marketization of spot transactions has become increasingly prominent

thus the construction of the day-ahead electricity market is imminent. A bilateral game model is established with the incomplete information between power supply and demand sides in the day-ahead electricity market

which is aimed to provide a practical game scheme for both sides in the power transactions

so that both sides can obtain the greatest benefits in the power market. The model takes the direct power purchase price and amount as the key points of the game. For the part of the direct power purchase price

the generation cost factor is introduced and the co-integration theory is used to construct the relationship model between the direct power purchase price and the generation cost considering the error correction. The part of the direct electricity purchase amount is predicted by similar day method. Finally

the Nash equilibrium is used to find the solution of the bilateral game and the effectiveness of the proposed model is proved by an example.