Postharvest diseases caused considerable losses to harvested fruits during the process of postharvest storage, transportation and distribution. By now,postharvest pathogens of fruits were controlled primarily by chemical fungicides. Therefore,it is urgent to develop alternative methods because of the fungicide residual,the development of fungicide-resistant strains of pathogen, the environmental pollution and the threat on human health. As one of the new and safe methods for postharvest diseases of fruits,various antagonistic yeasts have been isolated and identified as the potential antifungal biocontrol agents against postharvest fungal pathogen in the past thirty years,some yeasts-based products have obtained the permission to be used commercially. In recent years,mechanism of action of antagonistic yeast involved in the biocontrol of postharvest pathogens has been researched extensively,including the yeast′s competition for nutrients and space,the production of antifungal compounds,the resistance of fruit tissue and mycoparasitism. In this paper,the above-mentioned mechanisms of yeasts were reviewed,which will be helpful for selecting appropriate formulations and methods of application.