The invention discloses a welding head mounting and clamping device. The welding head mounting and clamping device comprises a first metal block and a second metal block which are connected with an anode and a cathode of a power source respectively, the first metal block is provided with a first through hole, an insulating sleeve arranged on a machine head slide shaft of a welding machine can be embedded in the first through hole, the first through hole is fixed to the insulating sleeve through an abutting screw, and a narrow slit is formed in the first metal block in the axial direction of the first through hole and penetrates to the outer side of the first metal block from the inner side of the first through hole, a fastening screw used for adjusting the size of the opening of the narrow slit is further arranged in the plane perpendicular to the narrow slit. According to the welding head mounting and clamping device, by forming the narrow slit in the first metal block and adjusting the size the opening of the narrow slit through the fastening screw, then the size of the diameter of the first through hole can be adjusted, so that the fixation of the first through hole and the insulating sleeve is more stable, and therefore the fixation stability of a welding head clamp and the machine head slide shaft of the welding machine is improved.