A remote controller, a remote-control system and a control method thereof are provided. The remote controller includes a motion sensing circuit and a wireless communication circuit electrically connected to the motion sensing circuit. The motion sensing circuit determines whether or not a motion of the remote controller complies with one of multiple reference motions. When the motion of the remote controller complies with one of the reference motions, the wireless communication circuit is switched from a sleep state to a working state. The wireless communication circuit that is in the working state determines whether or not a received signal strength indication between the remote controller and a controlled device is greater than or equal to a strength threshold. When the received signal strength indication is less than the strength threshold, the wireless communication circuit is switched from the working state to the sleep state.