Interrupted sampling repeater jamming (ISRJ), which is generated by digital radio frequency memory (DRFM), has become a hot topic about electronic counter measures (ECM). The paper has proposed an ISRJ suppression algorithm based on numerical statistical characteristic analysis and clustering. First, preprocess the echo data to improve signalnoise ratio according to the numerical statistical characteristic analysis. Next, apply the algorithm of clustering to the echo so as to identify ISRJ and obtain the parameters of ISRJ. Then, reconstruct the jamming based on the ISRJ information from previous step. Finally, use the reconstructed jamming to suppress ISRJ. The simulation result shows that the proposed method can identify ISRJ successfully when SNR of echo is higher than -10dB.