Suppression subtractive hybridization (SSH) has been recently reported as a differential display technique at the basis of suppressive polymerase chain reaction(PCR). This technique has such advantages as easy and feasible, highly specific, capable of separating the low abundant specific fragments. Now it has been successfully applied in the study of tumors, developing biology, immune regulations, etc. Here we summarized its principle, method, and advances in the study of tumors, then analyzed its merits, defects, and applicable potentials.