The invention discloses an adjustment device of a laser-electric arc combined welding gun. The adjustment device comprises a laser head clamping sleeve and the welding gun. The welding gun is connected with the laser head clamping sleeve sequentially through an angle adjustment mechanism, a front-and-back adjustment mechanism, an up-and-down adjustment mechanism and a left-and-right adjustment mechanism. The laser head clamping sleeve is connected with a laser welding head. The angle adjustment mechanism comprises a welding gun clamping sleeve, a guide column clamping sleeve, an angle adjustment guide column and an angle adjustment screw. The front-and-back adjustment mechanism comprises a sliding guide rail, a rack and a gear in the front-and-back direction, wherein the rack is meshed with the gear. The up-and-down adjustment mechanism comprises a sleeve base, a high-low-direction guide column with a rack and a high-low-direction gear, wherein the guide column is meshed with the gear. The left-and-right adjustment mechanism comprises a left-and-right adjustment screw, and the left-and-right adjustment screw penetrates through a long hole in the sleeve base to be fixed to the laser head clamping sleeve. Operation is easy and convenient, the structure is reasonable, manufacturing is convenient, the position of laser beams of the welding gun in three-dimensional space can be accurately adjusted, and the angle adjustable range is greatly expanded.