In order to explore the mutagenic and anti-mutagenic effect on the different storage periods of Korean soybean paste. In this study, on the basis of detecting mutagenicity effect by modified Ames test, and detecting the anti-mutagenic effects of the Korean soybean paste samples with different storage time have on Mouse bone marrow micronucleus test. Result: the mutagenicity of Korean soybean paste were negative; Anti-mutagenic effect were enhanced with the extension of storage time and the concentration, the anti-mutagenic effect of TA100 and TA98 strains induced by Trp-p-1 and MNNG reached the maximum value at 12 months of storage. And there was a dose-concentration-response relationship. At the same time, there was significant inhibitory effect of Korean soybean paste extracts with storage 12 months on mouse bone marrow micronucleus, the highest inhibition rate was up to 46.5% in the test. The results showed the strongest anti-mutagenic effect of Korean soybean paste was which stored for 12 months and no mutagenicity found, provided an experimental proof for the further development of Korean soybean paste in nutritional, functional, and for basic research and the promotion of cancer diet.