Abstract: In this paper the relevant modifications have been made for program for numerical analysis of stress-strain cycles during GTA spot welding of two dimensional and axle symmetrical thin plates. The stress-strain cycles during GTA spot welding of Titanium alloy plates have been calculated using modified program and their results have been compared with those of Aluminium alloys and stainless steel. The features of the welding thermal elasto-plastic stress-strain cycles of Titanium alloys have been revealed from those results. The program of numerical analysis has been examined by means of Moire technique specially developed for assessing welding thermal strains. The calculated results and the experimental tones in transient and residual conditions are identical, thus shows that the analysis program could authentically describe the stress-strain cycles during GTA spot welding.