Considering the complex working environment and the high risk of oil spill of single-point mooring systems, it is necessary to do risk evaluation and establish the corresponding monitoring, maintenance, supervision and management system for the whole work flow which includes people, various equipment, environment and so on. We study the single-point mooring system with failure mode and effects analysis (FMEA), and investigate the oil tanker with fault tree analysis (FTA). Through the analysis of the single-point mooring system, the key parts failure modes and the reasons and effects of the failure are obtained. Through the FTA, we get the various basic events that may cause the oil spill. On the basis of the analysis, we can make relevant maintenance policy and supervision and management measures to reduce the risk of oil spill.