In view of the problem that the opening and closing characteristics of a safety valve can not meet the design requirements,liquid flow force analysis is needed.The flow field simulation and analysis was carried out to study the flow characteristics of the fluid inside the safety valve and the action law of liquid flow force .It is concluded that the main reason for the inadequate opening and closing characteristics of the safety valve is the unreasonable outlet structure of the safety valve.Then,based on the results of dynamic analysis and CFD simulation,the AMESim simulation model was built and the experimental curve was repeated.By increasing the outlet position and expanding the outlet diameter,the structure of the safety valve was optimized.The results show that this method can effectively improve the opening and closing characteristics of the safety valve and make its closing pressure meet the requirements of normal closing.