To solve the problem that the adjusting of welding parameters depend on experience, experimental scheme of TC4 light gauge laser welding is designed with orthogonal regressive rotation design. Mathematic model of laser welding parameter (current, pulse width, frequency) and prediction response numeric (tensile-strength) is established based on response surface. Influence regular pattern of each processing parameter for welding procedure is analyzed by the mathematic prediction model. As the analysis shows that welding current has main effects on the tensile properties of the laser welding joint and not only the influence of pulse width and frequency on the tensile properties of the joint has obvious interaction, but also the impact effects of any single factor for pulse width or frequency are less than welding current. Best-fit welding parameters for TC4 sheet of δ=1.5 mm are obtained, and relevant test on which is performed. The results show that the mathematic model is consistent with the actual well.