The inhibitory effect of Coptis chinensis and Forsythia suspensa on six kinds of common microorganisms causing food contamination was detected,and the formula of synergistic effect was optimized.The inhibitory ability of Coptis chinensis and Forsythia suspensa on E.coli,S.aureus,B.subtilis,M.luteus,H.anomala and Aspergillus niger was measured based on Inhibition zone diameter and MIC,and their combined antimicrobial activity was judged based on FIC.For M.luteus,the vitro synergistic effect of Coptis chinensis and Forsythia suspensa was both optimized by formula test.The combined inhibitory ability of Coptis chinensis and Forsythia suspensa on these six microorganisms resulted in either synergy or activity effect.The best ratio of Coptis chinensis and Forsythia suspensa which is 4.523∶ 5.477,shows the greatest in vitro synergy effect on M.Luteus.