The car-mounted mobile single sided spot welding machine is one kind of DND3-Series, which is suitable for the spot welding between the Low carbon steel, Stainless steel And Low carbon steel framework Structures: Circuit, welding transformer, the waterway system of Circulation cools, Control system, two water-cooled cables connected with welding transformer, welding Gun and Electric Plier. There are four wheels on the bottom for the convenient movement And the top of the machine is a hanging board for the convenient hanging. When welding, the spot gun can be free to use the full range and it is easy to operate.