Modeling an accurate and effective heat source is a challenge when describing the thermal behavior of wheel/rail contact, conventionally modeled using Goldak’s heat source. This Gaussian distributed model transplanted directly from the welding field is quite different from the ellipsoidal heat source on the contact patch. An innovative heat source model which reflects the shape and size of contact patch was created based on the energy equivalence in this study. The thermal behavior of the wheel/rail contact was described by using this heat source moving along the rail. Numerical simulations based on a three-dimensional (3-D) finite element (FE) model validate that the proposed heat source model is valid as the relative errors of the peak temperature between the proposed and previously published heat source model are less than 4.45%. The distribution of the contact temperature on the rail surface reflects the shape and size of the contact patch. The semi-ellipsoidal distributed temperature obtained by the proposed elliptic cylinder model is more precise than the Gaussian distributed temperature obtained by the conventionally used Goldak’s model. The proposed elliptic cylinder model has the advantages of simple structure and flexible model variables than the ready-made Goldak’s model in commercial software.