This paper aims to introduce a novel method in terms of risk analysis and control of FPSO oil and gas processing system. The Failure Mode and Effect Analysis (FMEA) is implemented to identify the critical equipment and typical failure modes, in order to improve the accuracy and pertinence of model establishment. A Petri Net model is then developed based on FMEA results and the correlation analysis between different components. The input reliability data are primarily collected from Offshore and Onshore Reliability Data (OREDA), and the maintenance information is assessed by industry experts, using fuzzy synthetic evaluation method. This paper focuses on the accuracy, rapidity and feasibility in the modeling and solution process, and considers the influence of weather factors on the maintenance operation and limited maintenance crew number, forming a complete set of reliability and maintenance strategy optimization analysis method of FPSO oil and gas processing system. The results contain system reliability, availability, and maintenance information. The proposed approach can reveal the risk feature of the system and provide corresponding risk control scheme.