The mooring system of Nanhai Tiaozhan FPS platform faces the second life extension, it is necessary to conduct the risk assessment of the mooring system to ensure the safety operation of the offshore floating production facilities and scientifically formulate the life extension scheme of the mooring system. The risk matrix method recommended by International Organization for Standardization (ISO) is used to analyze the risk from two dimensions: hazard frequency and consequence of risk events, the hazards of FPS platform mooring system are classified and identified, each hazard is assigned to the corresponding frequency and consequence category, among which the frequency is described by the possibility of fact and the consequence is assessed from the aspects of people, assets, environment and reputation, and then the risk of each hazard is assessed and ranked. The results show that the prominent hazards of the mooring system at present are severe typhoon and abrasion. Some suggestions are proposed to reduce the risk with the combination of the current situation of the mooring system.