That the oil and gas exploration and development is extending into deep water proceeds the rapidly shift to subsea production system. However, complex subsea equipment and frequency offshore accidents aroused the concern on the risk assessment of subsea system. The paper illustrates the hazard aspects which should be focused on in the subsea equipment compared with the surface equipment. The hazards identification and risk analysis on subsea X-tree system is carried out. A general risk-prevent process of subsea X-tree system is illustrated, so does the reliability analysis process. Besides, some commendations on subsea detection and maintenance are presented in the paper.