Abstract: A strain of potential antagonistic yeast was isolated from mulberry fruits, which showed the biocontrol efficacy against postharvest decay of grapes. By molecular biological identification and biochemical examination, the antagonistic strain was identified as Saccharomyces cerevisiae. The antagonist showed significant biological control efficacy against postharvest decay of grapes caused by Aspergillus niger. When the concentration of the antagonist was higher, the disease incidence was lower. The concentration of S. cerevisiae was 1×108cfu/mL, the inhibition effect of grapes diseased by Aspergillus niger was best. Rapid growth of the antagonists in wounds was observed at 20℃ and 4℃. S. cerevisiae significantly reduced the natural development of decay and did not have significant effect on postharvest natural quality.