Abstract: In order to obtain the temperature distribution of the wingding in the oil-immersed power transformer, the multi-physical field coupled finite element method is proposed. The paper firstly achieves the velocity distribution in the oil duct by solving the governing equation of fluid field used least-square finite element method. Then, the uniform governing equation of temperature field for the oil fluid and winding coupled heat transformer problem is constructed. And the upwind finite element method is used to solve the uniform heat transformer equation, in which the fluid-solid coupled interface condition can be satisfied automatically. Considering the influence of the temperature on the physical parameter of the material and the joule loss of the winding, the fluid field and temperature filed is iteratively solved to obtain the final temperature distribution. The proposed multi-physical field coupled method is applied to calculate the temperature of the wingding in an oil-immersed power transformer, and the result of the proposed method is compared with software Fluent. It shows that the fluid distribution computed by the proposed method is in very good agreement with the results calculated by the commercial software Fluent, and the difference of the temperature is less than 1K, which verifies the accuracy of the proposed method. Meanwhile, the temperature distribution compared with the result of classical Galerkin finite element method shows that the proposed upwind finite element method can efficiently suppress the nonphysical oscillation, which improves the stability of the numerical method.