The aim of the present work is to study effect of flavonoid on pre-symbiotic growth of arbuscular mycorrhizal fungi cultured in vitro.Effects of flavonoid compounds (quercetin,naringin,rutin,umbelliferon,biochanin A,zeatin riboside,flavanon,apigenin,genistein and formononetin) on spore germ ination,hyphal growth and hyphal differenatiation of arbuscular mycorrhizal fungi Gigaspora margarita and Glomus geosporum were examined.Results show that quercetin and rutin stimulated spore germination and hyphal development of Gi.margarita,and quercetin,ranging between 0.5 μmol L^-1 and 8 μmol L^-1,significantly promoted hyphal growth,hyphal branching and formation of clusters of auxiliary cells,increasing hyphal length,number of hyphal branches and clusters of auxiliary cells by two or three times as compared with the control group,while the other types of flavonoids showed little effect on presymbiotic growth of Gi.margarita.Appropriate in concentration,formononetin,genistein and naringin,stimulated had positive effect on spore germination,hyphal growth and hyphal branching of Gl.geosporum,and apigenin,flavanon and naringin didformation of secondary spores.Biochanin Amerely had some stimulating effect on spore germination of Gl.Geosporum.Variation of the effect of flavonoids on development of arbuscular mycorrhizal spores depends on type and concentration of flavonoid compounds involved,and different flavonoids play different roles in promoting spore germination,hyphal growth and hyphal branching and formation of secondary spores at presymbiotic growth stage of the AM fungi.To study mechanism of flavonoids influencing presymbiotic development of AM fungi will help understand interactions between microbe and Plant.