Centrifugal compressor is one of the most widely used equipment in offshore platform. The inlet and outlet piping of compressor is important for the whole piping system but high risk for the safe operation of offshore platform. The inlet and outlet nozzles of compressor are strictly limited by force, and the 1~2 spring supports for piping are generally used near the inlet and outlet to reduce the force of nozzles, which increases the difficulty of installation, commissioning and maintenance. The boundary condition, stress calculation condition, stress analysis method and acceptance criteria are introduced. Based on an offshore natural gas processing platform in Bohai, the CARSAR II software was used to calculate the stress of the inlet and outlet piping of centrifugal compressor. The design of the inlet and outlet piping was optimized without using spring supports. The results show that the piping stress, displacement, natural frequency, force of compressor nozzle, flange leakage, and the force of the piping support satisfy the requirements, and the on-site operation is well.