The invention discloses a mounting tooling of a car lamp rear cover. The mounting tooling comprises a pressure bar and a tooling table, wherein the tooling table comprises a mounting platform, an air cylinder and a pattern die; the pattern die is arranged on the mounting platform; a groove matched with a car lamp lampshade is formed in the upper part of the pattern die; the air cylinder is positioned above the pattern die; the lower end of the piston rod of the air cylinder is provided with a pressure head; a pressure bar head is arranged at one end of the pressure bar; a pressure groove matched with the outer end surface of the rear cover is formed in the end surface of the pressure bar head; and the other end of the pressure bar corresponds to the pressure head. Through the adoption of the mounting tooling, the rear cover can be quickly mounted in place, and the mounting is achieved through the compaction of the air cylinder, so that the labor intensity is low, and the production efficiency is high; besides, the pressure bar head is matched with the outer end of the rear cover, so that the stress is uniform, the mounting uniformity of the product is good, and the mounting quality of the car lamp rear cover can be greatly improved.