Welding 10 mm Q345B steel plate by using laser-MAG hybrid welding, the effects of laser power, MAG current, defocusing amount and welding speed on weld penetration and width were analyzed by multiple linear regression method. The MATLAB algorithm was used to optimize the model and get the best combination of welding process parameters. The experimental results show that when the laser power is 3 kW, the current is 320 A, the defocusing amount is-2 mm, and the welding speed is 8.3 mm/s, the weld penetration width ratio is maximized, and the verification result is not more than 5% from the actual value, the mathematical model can effectively predict the welding quality.