With bacteria and fungus that seperated from Pleurotus ostreatus as research object,different ratio of guality to liquid of garlic and ethyl acetate was prepared.The inhibition effect of garlic extract on competitive microbes in mushroom production was studied by inhibition zone method.The influence of garlic extract on Pleurotus ostreatus mycelium growth was also analyzed through mycelial growth rate method.The results showed that garlic and ethyl acetate (w/v) 1∶2 extracted for 48 h,which inhibition effect was remarkable.Added garlic extract 1% of medium content in the culture medium of pH 8～9,which didn’t affect the growth of Pleurotus ostreatus mycelium,but could enhance the inhibition effect on various competitive microbes.