Abstract: In Over the Horizon (OTH) radar, the band is limited to lots of crowded and powerful interference. It is difficult to find an uncontaminated wide band, which leads to low range resolution and lower signal to interference ratio(SIR).This paper analyzes the degradation of pulse compression sidelobe due to the interference input power, bandwidth and location when notch filter is used. The adaptive interference cancellation technology within a required bandwidth is presented. It followed that this method can eliminate interference while not causing signal loss and can lead to lower sidelobe after pulse compression. The detection probability has increased greatly.