The invention relates to the field of ground rail robots, in particular to a crawling ladder welding device based on a ground rail robot. The technical problem to be solved is to provide the crawling ladder welding device based on the ground rail robot. According to the technical scheme, the crawling ladder welding device based on the ground rail robot comprises a material placing assembly, a welding assembly and the like, and the material placing assembly is connected with the welding assembly. When the crawling ladder welding device is used, cutting is carried out on an L-shaped cross rod in advance, the two ends of a horizontal part of the L-shaped cross rod exceed the two ends of a vertical part respectively, then the two ends of the horizontal part are lapped on two vertical rods respectively, the the welding operation is carried out, and therefore the problem of poor stability caused by a small welding area is eradicated, the L-shaped transverse rod is perpendicular to the two vertical rods at the same time and then the welding operation is carried out, the phenomenon that the transverse rods are inclined after welding is eradicated, welding is sequentially carried out on the six transverse rods through a ground rail, meanwhile, automatic lubrication can be achieved, and lubricating oil is prevented from dripping into the device.