Abstract: Taking two-year old Ginkgo seedling ’Jiafoshou’ as the material,the ginkgo seedlings were sprayed with methods of different concentrations biological nano-selenium,the experiment studied the effects of different concentrations of bio-nano-selenium treatment on the physiological indexes and flavonoid content of ginkgo leaves at different growth stages,which hoping to provide a reference for ginkgo cultivation and efficient use of bio-nano-selenium.The results showed that the contents of chlorophyll,soluble sugar and total flavonol glycosides in the G.biloba leaf with 1.6 mmol·L^-1 biological nano-selenium treatment increased in July and September,which were 43.87%,59.92%,43.99% and 13.86%,18.60%,35.04% higher than control group,and the improvement was significantly different.Paying attention to the 1.6 mmol·L^-1 nano-selenium treatment group,the total flavonol glycoside content in June,July,September and October were 6.78%,31.84%,36.70% and 9.78% higher than it in August,which were significant differences in July and September.In conclusion,it could obtain the best quality G.biloba leaf if 1.6 mmol·L^-1 biological nano-selenium fertilizer was applied and leaf is collected in July and September.