The electromagnetic fields of a canned motor was analyzed by using the improved finite element method, and the eddy loss in motor was obtained. The correlated thermal conductivity and the coefficient of heat transfer were also determined, based on which the numerical calculation model of temperature field of the canned motor was established. Taking the eddy loss from electromagnetic field calculation as the heat source of temperature field, the three-dimensional temperature fields of canned motors' stators were calculated. The calculated results show good agreement with the experiential data, which indicated that this method has good accuracy and the reliability for dealing with canned motor thermal behavior. In addition, the influence of stator can thickness and material on motor thermal behavior was also studied, and some beneficial conclusions could be obtained.