Abstract: The plasma arc welding of TA2 pure titanium plate with 4 mm thickness was simulated by using finite element software ANSYS. The distribution feature of transient temperature field of weld process was calculated and analyzed,and then indirect coupling of thermal- stress was fulfilled based on temperature field,the stress distribution and weld distortion of TA2 pure titanium joint by plasma arc welding are calculated.Resultsshow that the weld appearance of numerical simulation was basically consistent with welding experiment,and the character of temperature field is ellipse with high temperature gradient at the welding zone; The stress state of welded joint presents the characteristic of tensile stress and compressive stress coexist,and the thermal stress is the main factor while the transient distribution of welded joint and the plastic stress is the main factor in the residual stress; after welding is finished,the distortion presents angular distortion,and maximum deformation reach to 2. 3 mm.