The advantages of laser welding process include high energy density, high precision,small heat affected zone and welding deformation,which is especially suitable for the welding of automobile precision parts. Laser penetration welding is used instead of arc welding to connect recliner assy and 3 mm thick connecting plate,meanwhile,there is no need to reserve process opening on the parts and the product design is more flexible. The influence of each process parameter on the welding quality is analyzed by adjusting the laser welding parameters. When the welding parameters are designed as laser power of 2 200 W,welding speed of 20 mm/s and negative defocusing amount of5 mm,the appearance of weld is good,and multiple welds are closely arranged and the penetration is over 3.9 mm.