Abstract: The ultra-wide band radio frequency technology has been widely used in communication, radar, ECCM and other fields. Rapid judgment and convenient and accurate recognition are required by ultra-wide-band microwave signal system in the future, so, this paper designs a kind of adaptive frequency selective switchover network applicable for the signals from DC to 40 GHz microwave signal. The design adopts 3-section processing, respectively adjusting the signal amplitude of each section, then perform filtering, detection, comparing, D/ A conversion, logic judgment, control and drive, to realize accurate recognition, judgment and switchover of different frequency bands, in this way, it implements switchover ability of small signal in microsecond (μs), large signal in millisecond (ms) within full frequency band, and verifies the validity of this design.