The invention discloses a connector locking device which comprises a plug sheath, a locking device body and a socket sheath. The socket sheath is mounted in the chamber of the plug sheath. Furthermore the socket sheath is provided with a retreating preventing head. One end of the locking device body is hinged with the socket sheath and engages with the plug sheath. The locking device body is provided with a retreating preventing surface which matches the retreating preventing head. According to the connector locking device, the plug sheath and the socket sheath are locked through an engaging structure between driving teeth on the locking device body and the driven teeth on the socket sheath and a matching structure between the retreating preventing head and the retreating preventing surface. According to the connector locking device, through a gear engaging type power assisting mechanism, a lever principle is utilized for reducing a connector combining force and furthermore realizing more compact connector structure, reducing product size, saving automobile body space and satisfying an automobile industry development requirement.