A Wi-Fi/radio frequency (RF) converting device includes a Wi-Fi transceiver, a multiplexing converting module, and a RF transceiver. The Wi-Fi transceiver receives a Wi-Fi control signal from a control signal generator. The multiplexing converting module receives the Wi-Fi control signal from the Wi-Fi transceiver and converts the Wi-Fi control signal into a RF control signal. The RF transceiver receives the RF control signal from the multiplexing converting module and sends the RF control signal to a plurality of electric elements. An RF extension device may be provided to share the signal transmission between the electric elements and the Wi-Fi/RF converting device.