The invention discloses a trolley case locking device and a locking method. The trolley case locking device comprises a sensing piece, a sensed piece and a sensing piece locking device, wherein the sensing piece is connected to a zipper puller assembly of a trolley case, the zipper puller assembly is composed of a zipper puller and a zipper handle, and the sensing piece can swing back and forth below the zipper handle; the sensed piece comprises a sensed action device and a sensing piece locking control unit, the sensing piece locking control unit is in communication connection with the sensed action device, and the sensing piece locking device is used for being connected with the sensing piece after being driven to act so as to lock the position of the sensing piece; and when the zipper puller assembly is pulled to drive the sensing piece to reach the position of the sensing piece locking device, the sensing piece senses the sensed action device, and the sensing piece locking device is driven to act by the sensing piece locking control unit. With the trolley case locking device and the locking method, the antitheft performance of the trolley case is greatly improved, and the safety level of the trolley case is improved when people travel.