The invention provides a welding gun cleaning device and a welding wire cutting device. The welding wire cutting device comprises a rack, a wire cutting machine cover, a through beam type photo electric sensor, a wire cutting machine, a left support arm, a right support arm and a waste collecting box, wherein a concave arm which extends towards left is arranged on the upper end surface of the rack, a strip-shaped through groove is formed in the concave arm, the rack is connected with the wire cutting machine cover, the through beam type photo electric sensor main body and an electromagnetic valve of the wire cutting machine are fixed inside the rack, the left support arm is L-shaped, the strip-shaped through grooves are formed in both the left support arm and the right support arm, the left support arm is fixed on the upper end surface of the concave arm, a light emitter is fixed on the left support arm, the right support arm is fixed on the wire cutting machine cover, and a light receiver is fixed on the right support arm. The device can collect the cut waste, uses the photo electric sensing control way to control the cutting operation, and avoids the phenomenon of error alarm caused by that a welding robot collides; the device can be directly used for the welding robot which is few in output signal, the positions of the light emitter and the light receiver can be adjusted, and the device can be suitable for the arms of the welding robots in different appearance sizes.