Abstract: In order to optimize the flow characteristics of a triple-eccentric butterfly valve which control the superheated steam, a CFD model was established, and the three-parameter S-R-K equation of state was used to simulate the superheated steam density, and the flow coefficient was taken into a flow characteristic curve diagram. The graph indicates that when the opening is 80°~90°, the flow characteristic of the triple-eccentric butterfly valve deviated seriously from the equal percentage characteristic. Aiming at this problem, the shape and structure were considered and then 10 schemes were worked out. According to each of the schemes, the flow coefficients were calculated based on fitting method. Then the optimal scheme was found.To further, the effectiveness of the optimization scheme was verified by analyzing the pressure field and velocity field. The results indicate that the change of the distance between the bottom surface of the butterfly plate and the outer end surface of the pressure plate has the greatest advantage on the improvement of flow characteristics.