Abstract: Aspergillus Oryzae HN 3.042 spores ( AK) and Glycos-esterifiable Monascus ( GK) were mixed, being applied in Koji-making in this article. The synergy effect of GK and AK in different ratio on physicochemical properties of soy sauce and its optimal ratio was investigated.The result revealed that adding GK could inhibit the activity of acid protease while significantly increase the total nitrogen and amino acid nitrogen and then decrease slightly.The activity of anti- oxidation could be improved by adding GK at a certain extent.When 0.5‰ of AK and 1.5‰ of GK were mixed, the DPPH free radical scavenging activity came up to the highest.Otherwise, total nitrogen had significant correlation with the changes in amino acid nitrogen ( p < 0.01 ) , and total acid had positive and negative correlation respectively in total nitrogen and the DPPH free radical scavenging activity ( p < 0.05) .