Taking Q345B steel plate with a thickness of 10 mm as the base material, a series of studies investigated the influence of main process parameters of laser-DP TIG hybrid welding on the formation of welding seams, so as to provide experimental basis for the optimization of composite welding process. The experimental results showed that the laser acts as a shock and agitation on the molten pool, which improves the fluidity of the molten pool and forms a flat weld, and weld width is dominated by arc current; the laser power has little change to the weld width, and the weld penetration depths increases with the increase of laser power; the welding melt depth as well as the width increase first and then decrease with the increase of defocusing amount(-2~3mm); the welding penetration is bigger while the laser is in front of the arc.