Objective To investigate the effects of litchi polyphenols on growth and development of Peronophythora litchii.Method Polyphenols were extracted from litchi pericarp by solvent extraction. The effects of polyphenols on colony morphology, biomass, germination mode of sporangium, zoospore germination and oospore number of P. litchii were analyzed by phytopathological research methods.Result With the treatment of litchi polyphenols at 150 to 300 μg·mL^-1, the hyphal colonies of P. litchii appeared dense, hyphal dry weight and sporangia number were significantly reduced, and the sporangia germinated to release zoospores. With the treatment of litchi polyphenols at 100 to 300 μg·mL^-1, zoospores germination was significantly increased while sporangia germination was significantly suppressed. Oospore was hardly observed in PDA control without litchi polyphenols. When litchi polyphenols in the media reached 100 μg·mL^-1, the produce of oospores was 10.8 mm^-2.Conclusion Litchi polyphenols involve in the regulation of the growth and development of P. litchii, can suppress the growth of P. litchii and sporangia germination, indicating their potential for developing new safe biogenic fungicides.