This article introduces the function of automatic monthly closing module of the BIM platform, and analyzes the usage of this module function with an example. By using the accumulated feedback engineering quantity data automatically calculated from the 3D model of BIM platform and the entered contract unit price information, automatic calculation of total monthly settlement amount can be done so as to realize the automatic settlement of engineering quantities. The subcontractor and the general contractor can work collaboratively online, which improves the accuracy and work efficiency of project cost management and reduces the workload of manual calculation.