A system for transmitting radio signals via cable television broadband networks includes a wireless access device, an adapter device and a plurality of distributing devices. The wireless access device is disposed in one of spaces for receiving and transmitting radio signals. The adapter device has a first input side for receiving the radio signals, a second input side for receiving cable television broadband signals, and an output side for outputting mixing signal that compose of the radio signals and the cable television broadband signals. The distributing devices are disposed respectively in the spaces, and connected in sequence. Each of the distributing device has a mixing signal input side for receiving the mixing signals, an antenna for outputting the radio signals, a connector for outputting the cable television broadband signals, and a mixing signal output side for outputting the mixing signals to the mixing signal input side of another distributing device.