The invention discloses a full-automatic multi-operation-point position integrated welding maintaining device. When the device is used, firstly, a maintenance man uses a car lifting device to lift a car wholly and then holds a hand rail and pushes the device with hands to move the whole device to the bottom of a car chassis, a welding gun is located under an abraded part of the car chassis, the maintenance man turns on a first motor, the height of the device is adjusted through the first motor, the position of the welding gun, and the position of a spray gun and the position of a polishing piece are adjusted sequentially through a second motor, wherein the second motor is a stepping motor. The chassis is repaired in a manner of welding, spraying and polishing in sequence. The full-automatic multi-operation-point position integrated welding maintaining device prevents the situation that due to abrading and rusting of a base plate, the overall driving stability of a car is reduced, so that the comfort of sitting in a car is improved for people.