The cylindrical FPSO designed by DANA Petroleum Company of the United Kingdom is taken as the research object. The upper structure and arrangement of the conventional FPSO and the cylindrical FPSO are compared. The overall strength of the cylindrical FPSO upper structure is determined by the finite element method. The local strength analysis for the bulwarks, public areas and blast walls is also carried out. It is concluded that: cylindrical FPSO is more economical than ship FPSO, with greater resistance to overturning and deck load capacity, using fewer tubes cable; the design structure of the cylindrical FPSO meets the strength requirements of offshore work and is of practical application value.