Frequency shift interference can produce high fidelity false targets for the range-Doppler coupling characteristic of LFM signal. According to the peak characteristics of pulse echo by compression and the principle of dechirp， the interference suppression method based on signal reconstruction and cancellation is proposed. Firstly， the frequency of the signal by dechirp is estimated， and the dechirp interference signal is reconstructed. Secondly， the normalized average detection threshold is defined for the dechirp signal， and the minimum threshold is used as the objective function of interference suppression. Finally， the interference suppression factors corresponding to the minimum normalized average monitoring threshold are calculated by global search， and interference suppression is realized by cancellation. The simulation shows that the energy of residual interference component is more than 20 dB lower than that of target echo in the output signals by pulse compression， which shows the proposed method can suppress multi-frequency shift interference effectively.