Abstract: The construction of the new power system in China is facing the challenge of a shortage of flexible resources, and it is urgent to exert the adjustment ability of load side. As the mutual interaction between the power grid and load becomes more frequent, more load aggregators participate in market transactions by integrating jurisdictional flexible resources, resulting in the break of the market equilibrium dominated by the power generation side in the past. In order to study the game strategy of multiagent load aggregators, a bi-level bidding model of load aggregators under energy-reserve electricity market is constructed, and multiple scenarios are introduced to describe the influence of bidding uncertainty of non-decision makers on the market equilibrium. The multiple bi-level models are transformed into an equilibrium problem with equilibrium constraints（EPEC） model by strong stationary method（SSM）, and linearization methods such as big-M method and binary expansion approach are used for linearization. Results of the case validate the validity and effectiveness of the model and solving algorithm, demonstrating that the EPEC model based optimal bidding strategy of load aggregators is more in line with the actual market rules, which is helpful to optimize the load curve of the system and alleviate the tension between the supply and demand of flexible resources.