Abstract: The effects of welding parameters on the interface friction process was investigated by analyzing friction principle during the TC4 titanium alloys inertia friction welding.The temperature distribution in the joint is measured using thermocouple.The results show that the welding processes could be finished in less than 1.6 second and there is great temperature grads along the radius from the center (near 800℃) to the edge (1 360℃),which is validated by microstructure in the weld.The center of the joint is characterized by fine equiaxial grains and the edge is by lamellar structure.