Abstract: The ANSYS optimization methods have different computational efficiency for different problems. In this paper, the temperature stress of semi-circular ring in elastic mechanics is taken as an example to study the optimization problem of minimum temperature stress under different inner radii. The accuracy and convergence of different optimization methods are compared by setting three initial temperatures. The results show that the combination of sub-problem method and first-order method is the best. Based on this conclusion, the optimal calculation model of joint closure temperature for arch dam is established, and three methods are selected. The calculation shows that the above - mentioned combination method can obtain the optimal joint closure temperature, and the sub-problem method can meet the requirement under certain conditions.