The invention discloses an installation structure of a headlamp rear cover. The installation structure comprises a rear cover body, first fixing pieces and second fixing pieces, wherein the first fixing pieces are used for fixing one side of the rear cover body, and the second fixing pieces are used for fixing the other side of the rear cover body. An installation hole is formed in the bottom of each first fixing piece in a concave manner. An internal thread is arranged on the inner circumferential face of each installation hole. An external thread is arranged on the outer circumferential face of the top of each first fixing piece in a surrounding manner. A fixing groove used for clamping the rear cover body is formed in the side, facing the rear cover body, of each second fixing piece. Compared with the prior art, installation can be achieved by forming only 4 installation holes in an installation metal plate, the number of installation points is decreased, installation is convenient, installation stability of the rear cover body is ensured, and reliability of a whole lamp is increased.