Linear friction welding (LFW) has become a key manufacture and repair technology in the aeronautical engine manufacturing, especially in the blisk manufacturing. The kinematic equation during LFW was built, based on which the friction heat in the whole process was computed. With thermal- mechanical coupling technique, and considering the geometrical non-linearity, the material property non-linearity and the interface frictional non-linearity, a Finite Element Model (FEM) of temperature, stress and deformation fields were constructed. The distribution contour of temperature, plastic flow, stress and strain during LFW were plotted. The simulated temperature and axial shortening results were also validated by experimental data.