Abstract: An axisymmetric model of inertia friction welding process was established. By using finite element method of large elastic-plastic deformation, the effect of energy density on the temperature field, stress field, welding time and axial shortening was analyzed during inertia friction welding process. Result showed that the relationship between the energy density and the welding time was approximately linear. And the welding time as well as the axial shortening increased with the energy density. Furthermore increasing the energy density produced an increase in the temperature of the interface and also an increase in the flash generated during the welding process. The calculated data of the welding time and axial shortening during welding were in good agreement with the measured data.