In this study, 1mm thick Fe-Mn-Si shape memory alloy was welded by both sides using YAG laser welding. In a certain range of parameters, the optimal processing parameters for the maximum tensile strength are current 100 A, pulse frequency 3 Hz and pulse width 15 ms by orthogonal experiment. With the optimal processing parameters, the tensile strength of the welded joint can achieve 94% of base material,and the fracture appears in the center of welding seam and the surface morphology of welding seam is good. The influence of processing parameters on tensile strength of weld joint is directly embodied in cross-section of the welding seam morphology. In the laser welding, the tensile strength of nonpenetration in seam and hourglass shape welded joint is generally poor, and the perfect welded joint has conditions such as wide welding seam, deep penetration, weld pool filling and “non-hollow”. Most importantly, the central area in cross-section of the welding seam is the widest.