Abstract: In order to find out the characteristics of paclitaxel and cephalomannine in the branch of natural Japanese yew (Taxus cuspidata), the branch samples of natural Japanese yew were collected from Muling National Nature Reserve of Heilongjiang Province in different ages, sexes, months and site factors (slope aspects), and the content of paclitaxel and cephalomannine in the currentyear branches, the biennial branches and the perennial branches were measured with RPHPLC. The results were shown as follows: 1)for all of the branches of Japanese yew, the content of paclitaxel increased at the beginning and then decreased with age increasing, while that of cephalomannine decreased with age increasing. 2)When the DBH (diameter at breast height) was lower than 60 cm, there was no significant difference in the branch contents of paclitaxel and cephalomannine from trees sexes. But when the DBH was higher than 60 cm, higher paclitaxel and cephalomannine content was found in male trees than female trees. 3)For all of the branches, the content of paclitaxel and cephalomannine increased at the beginning and then decreased from April to October annually, and the maximum content of paclitaxel was found in August and September, meanwhile, that of cephalomannine was found in July and August. 4)For the currentyear branches, the content of paclitaxel and cephalomannine was affected by the site factors obviously. About the paclitaxel, the currentyear branches of Japanese yew individuals on sunny slope had higher content than that on shady slope when DBH was lower than 45 cm, and concerning cephalomannine, the limiting condition of DBH reduced to 30 cm. There was no significant effects of slope aspect on the content of paclitaxel and cephalomannine in the biennial and perennial branches.