Abstract: Under the background of the untying of trading organization and the increasing scale of bilateral trading,aiming to deal with the conflict between the trading results of decentralized decision-making in the market and the system security,the idea of bilateral trading security pre-check is proposed in order to figure out the trading security region and provide reference for the market organization.Necessities and modes of implementing the bilateral trading security pre-check are introduced firstly,followed by the modeling of trading feasible region in the energy quantity space.Three feasible pre-check models are then proposed combined with the geometrical properties of feasible region,along with a validation test method based on Monte Carlo simulation.IEEE 9-,30-and 118-bus system are employed to verify the effectiveness of the proposed model and pre-check method.Hopefully,the research can provide the technical reference for the construction of bilateral markets in an orderly manner by the pre-delineation of safety boundary in China.