Abstract: In order to study the mechanism of the welding parameters on the welding quality and optimize the welding parameters, optical microscopy and tensile testing machine were applied to observe and test the welding strength under different laser power, welding speed, material thickness. A 3-D physical model with axial symmetry was implemented to simulate the temperature field based on software ABAQUS and the effect of parameters on welding quality was obtained from orthogonal test. The results suggest that most important factor is laser power, followed by welding speed and material thickness. Meanwhile, higher temperature may cause bubbles to increase and affect welding strength.