Abstract: In order to adapt to the development of the domestic power market and respond flexibly to the uncertainty of electricity prices,the transaction process of power generation enterprises participating in the day-ahead power market was studied based on the current situation of the construction of the domestic power market.Considering the impact of the uncertainty of the day-ahead electricity price and the transaction cost of carbon emission rights,a joint bidding model of electricity generation companies’ dayahead electricity energy and ancillary service market was constructed. The uncertainty of price was simulated by constructing multiple electricity price scenarios,and the typical scenarios were obtained by the forward selection scenario reduction method based on Kantorovich distance. Based on the conditional value at risk（CVaR）,the risk preference of the bidding strategy of enterprises was quantified and modeled,and the bidding model was solved and the corresponding bidding strategy was obtained.The results of the example analysis show that the proposed model can provide an effective bidding strategy for enterprises and flexibly respond to the fluctuation of electricity prices. Compared with not participating in the secondary frequency regulation auxiliary service market,the income of enterprises is improved,and enterprises can change the risk factors in the model according to their own risk preferences to obtain an ideal bidding strategy.