Abstract: Based on the analysis of contact stress between valve body and valve base, the temperature field and stress field of rotary steam-distributing valve for underwater vehicles are simulated by three-dimensional finite element method of thermomechanical coupling under the complicated boundary conditions including displacement, force and heat conduction, and the influences of different valve base materials on the temperature field and stress field are compared. The results show that the biggest stress in the valve body appears at the intake bore where temperature is the highest and strain is the largest;the biggest stress approaching to the allowable value in the valve base is located at the surface of the gas bore;and the strength of the valve base can be largely improved when the new carbon-graphite composite impregnated with silver is adopted as its material.