Abstract: Based on models for heat transfer and solid mechanics of linear elastic materials with consideration of characteristics that the thermal physical properties of the titanium alloy change with temperature,the thermo-mechanical coupling model for friction stir welding(FSW) of high melting point alloy which is related to process parameters was established.The effect of welding speed on the temperature field,stress and strain of friction stir welding was investigated according to the established FSW model.The results show that with feed direction of stir head as the reference coordinate,the temperature field of FSW is oval-like distributed and large temperature gradient exists in front of the heat source.The transverse distribution of equivalent stress presents a characteristic of symmetry and bimodality,and the equivalent welding stress shows a Miller effect in lateral direction.The welding stress of FSW can be effectively decreased by decreasing the feed speed properly.It is important for understanding the FSW mechanism of high melting point materials by establishing the FSW thermo-mechanical coupling model of titanium alloy with high melting point.