The invention provides a software radio system based on frequency band compression, and relates to the field of software radio. According to the software radio system provided by the invention, in a sending end, a modulation signal is subjected to frequency band compression and modulation after being subjected to A/D conversion; after modulation, by D/A conversion on the signal, up-conversion and power amplification on the converted analog signal are completed by a radio frequency front end and then the analog signal is transmitted; after a receiving end receives the signal, the signal enters the radio frequency front end to complete signal amplification and down-conversion, and the obtained signal enters A/D conversion; after conversion, the signal is subjected to demodulation and frequency band recovery and then is input into D/A conversion so as to obtain the signal transmitted by the sending end. According to the software radio system provided by the invention, due to adoption of a frequency band compression method, performance requirements of software radio for a radio frequency front-end device can be effectively reduced, and the problem of serious distortion of a wide band signal, which is generated when the wide band signal passes through the radio frequency front end, is solved.