The performance of Flag Vessels impressed the viewers deeply at the opening ceremony of 2010 Shanghai Expo. Safety of the trainees is the key factor being considered by the organizer in the course of trainings, rehearsals and final performance. Complex chevron shape of fleet increased the risk, such as col-lision, grounding, waves damaging etc., which made it necessary to assess the risk of performers, especially the risk of man overboard. In this paper, Formal Safety Assessment (FSA) method recommended by Interna-tional Maritime Organization (IMO) was adopted to guarantee/assess the safety of the performers, especially decrease the risk of man overboard. FSA includes five steps in general, which are Hazard Identification (HAZID), Risk Assessment (RA), Risk Control Options (RCOs), Cost Benefit Assessment (CBA) and Rec-ommendations for Decision-Making (RDM) respectively. In this paper, Brainstorming and Fault Tree Analy-sis (FTA) methods were both used in HAZID step. Then the combination of the two indexes was employed to calculate the risk distribution of the fleet in RA step. One is the possibility of man overboard and the other is the consequence once the incident happens. Moreover, several RCOs were provided based on the risk distri-bution mentioned above. Finally, based on the results of FSA assessment, some suggestions were carried out to decrease the risk of performers according to CBA, like personnel arrangement according to risk degree of different areas in fleet. It has been proved that applying FSA method to the fleet of flag vessels can reduce the overall degree of risk and ensure the success of performance.