T he samples of Ginkgo biloba L .leaves of 30 years old tree were collected from April to November in Nanjing and were extracted w ith petroleum ether (60 ～ 90℃), purified with silical gel and analysed by HPLC.The results showed that the content of poly prenols in Ginkgo biloba leaves grew up month by month , while the yellow leaves had the highest content about 1 .1 % in fall.T he main polyprenol was C85 , about 38 % content and the nex t was C90 , about 32% .On the other hand , by analysing the leaves of y oung tree o f 3 ～ 5 years old in Pizhou city , Jiangsu Province collected in fall , the main w as polyprenol of C90 about 34 % ～ 35% , the second was po lyprenol of C85 about 24 % ～25% , compared with the leaves of old tree collected at the same time , the total content of polyprenols in the leaves of young tree was higher .