In the current code for design of arch dam in China，the temperature load in operation period is based on the analytical solution of infinitely long free plate，the effect of nonlinear temperature difference is not considered.This article is based on the calculation principle of relevant temperature load，taking the free plate as an example，the temperature field corresponding to the analytical method，the quasi steady temperature field method and the standard method is calculated，the rationality of the quasi steady temperature field analysis by using the program is explained.With the development of computer level，the quasi steady temperature field method can be used to calculate the temperature load of arch dams.