The utility model discloses a container rear cover self-locking device which comprises a lock hook, an adjusting device and a fixing seat. The lock hook is connected with a lock hook support seat through a connecting piece one and is connected with the adjusting device through a connecting piece two. The adjusting device is connected with the fixing seat through a connecting piece three. The fixing seat is connected with a vehicle frame. According to the container rear cover self-locking device, opening of the lock hook depends on the gravity of the lock hook, a return spring is canceled, and therefore opening failures due to reasons such as failure of the spring or assembling errors are avoided.