Abstract: The high-temperature and high-pressure valve is the key equipment of the wind tunnel system; it controls the generated high-temperature and high-pressure gas. In order to reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body, a cooling structure is set on the valve seat. This can significantly reduce the temperature of the valve body and seat. The effect of its structure on the cooling characteristic and stress of valve seat is studied and six main parameters that can completely describe the geometry of the cooling structure are proposed. The central composite design method is used to select sample points and the multi-objective genetic algorithm (MOGA) method is used for structural optimal design. Based on these, a modification method according to the main parameters for the valve seat is proposed. Results show that the cooling structure weakens the pressure bearing capability of the valve seat. Among the six main parameters of the valve seat, the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effect on the average stress intensity of the valve seat. An optimum design value is proposed. This work can provide a reference for the design of high-temperature and high-pressure valves.