Abstract: The key to narrow-band interference suppression is to suppress the interference while minimizing the loss of useful signals. Based on the time-frequency domain combined interference suppression method, and the completion of frequency domain interference parameter detection, this paper focuses on the key part of the interference suppression effect and useful signal loss-the design of the IIR notch filter. Based on the principle of zero-pole configuration, through theoretical research and detailed derivation analysis, it is proposed that by adding a pair of zero-poles and combining theoretical calculation to determine the polar angle and radius, the notch filter can obtain steeper band-stop characteristics on the premise of controllable pass-band gain and symmetrical transition band, which can theoretically reduce its usefulness. Compared with the current mainstream time-domain LMS algorithm, FFT-based frequency-domain-suppression algorithm and traditional time-frequency domain combination algorithm, simulation results show that the proposed method increases the peak-to-noise ratio by 53.47%, 8.369% and 5.907%, and the average output carrier-to-noise ratio by 5.147 2 dB and 2.003 7, and 0.508 6 dB respectively. More navigation signals are retained while effectively suppressing interference.