Aiming at the existence detection problem of suppression interference, a suppression interference detection algorithm based on Fractional Fourier Transform (FRFT) domain peak characteristic is proposed for pulse-compression radar. First, from the perspective of complete radar anti-jamming system, the general idea of combining the existence detection of suppression interference with target detection and interference classification is put forward.Secondly, based on the analysis of the difference between the peak characteristics of the FRFT domain LFM signals and the suppression interference signals, the peak order of the echo signal in the FRFT domain is selected as the characteristic parameter. Then, the sequential decision algorithm is used to determine the peak order of the multi-stage echo signal in the FRFT domain, thus to complete the existence detection of suppression interference. Finally, the effectiveness of the proposed algorithm is verified by simulation experiments.