A wireless transmission system is provided. The system includes a wireless transmission apparatus for sending radio signals in a selected frequency and a wireless reception apparatus for receiving the radio signals in the selected frequency and playing audio signals corresponding to the radio signals. The wireless transmission apparatus includes a scan unit for periodically scanning interference frequencies of candidate frequencies, and recording characteristics of each interference frequency; an evaluation value calculating module for calculating an evaluation value of each candidate frequency according to the characteristics of the corresponding interference frequencies; a frequency selection module for choosing one of the candidate frequencies as a current transmission frequency according to the evaluation values; and a transmission unit for sending radio signals in the current transmission frequency. A wireless transmission method is also provided.