On the basis of existing literatures,the conditions for hydrolyzing ginkgo flavonoids with purity (>85%) are optimized.The two undefined factors:constituents of hydrolytic liquid and the rate of flavonoid and volume of hydrolytic liquid are discussed.The hydrolytic solution:is V(CH_3OH):V(H_2O)=45:5,and w(flavonoids):V(hydrolytic liquid)=1 g:65 mL.Optimum conditions for production of quercetin,kaempferol and isorhamnetin from ginkgo are provided by HPLC method .