The present invention discloses an adaptive co-site disturbance suppression system and method capable of reducing the notch bandwidth. The co-site disturbance suppression system comprises a coupler 1, an orthogonal power divider 1, an orthogonal power divider 2, an adjustable attenuator 1, an adjustable attenuator 2, a correlator 1, a correlator 2, a detection unit 1, a detection unit 2, a controller, a synthesizer and a coupler 2. The adaptive control of calculating, determining, locking and releasing is carried out on the control amount of the adjustable attenuators via the detection units and the controller, so that the constant control amount of the adjustable attenuators can be realized, and accordingly, the attenuation of the co-site disturbance suppression system to the effective signals is avoided, and the notch bandwidth is reduced. The system can guarantee the situation that the received weak effective signals are not attenuated when offsetting the received interference signals, thereby guaranteeing the normal work of a receiver. The system has the bandwidth reduction effect, so that the system also can be used to reduce the transmitting-receiving frequency difference and improve the utilization rate of the spectrum resources.