The general assembly supporting block is an important supporting component of topside module of Floating Production Storage and Offloading (FPSO) during the whole construction. Based on a large FPSO topside module construction project, the support reaction of general assembly supporting block of topside module is calculated with the Structural Analysis Computer System (SACS) software, and the model building and strength check of general assembly supporting block of topside module are conducted with the Ansys software. The results show that the load carrying capacity of the two different types of general assembly supporting blocks can meet the construction requirements of the project, and the ground pressure is within the allowable range of foundation load carrying capacity.