The voluntary purchase mechanism of green electricity and the trading mechanism of green certificate are restricted by the economic development level, customers' environmental protection consciousness, etc. In this paper, the game-based competitive bidding model of green electricity and conventional power (coal-fired power) is constructed. The green electricity is inferior to the conventional power because of the restriction of cost and scale under the present bidding system without regard to the environmental cost. Suppose there's financial subsidy or transfer payment for the green electricity from the government or the government increases the emission cost of conventional power, we extend the above bidding model. The result shows that the green electricity can bid in the competitive power market.