The six-degree-of-freedom arc welding robot system ARCMAN-MP was used to vertical welding test,and the object of welding is the shield machine cutter head large thickness Q345B carbon steel plate. The edited vector library realized the precise swing of the welding wire in the vertical welding groove,and the vertical welding with good appearance was obtained,in the same times,a welding database was built. The mechanical properties were conducted by tensile and impact experiment,the microstructure was observed by metallographic microscope,and the fracture morphology was observed by scanning electron microscopy（SEM）. The results show that the high welding efficiency,good weld surface formation,low weld defect rate and high overall welding quality in the experiments,showing this welding method has high quality and feasibility.