Based on analysis of the characteristics of construction project transaction, this paper constructs a construction project bidding model by using mechanism design theory, with the minimum total cost of the tenderee as objective function, while participation constraint, incentive compatibility constraint, technical ability, and control price etc. as constraints. According to the characteristics of construction project transaction, this paper then analyzes the model with the help of Myerson's optimal auction theory, and puts forward the corresponding simplified model. Finally, according to the construction and analysis process, this paper proposes the application steps of the optimal bidding mechanism, and discusses the calculation method of the related parameters. The research results provide a general framework for the mechanism design of construction project bidding, while the detailed design still needs further study.