A ready-made Chinese herb containing the glycosides of Tripteri-gium wilfordii ( GTW ) have been reported to cause testicular atrophy in men. Various fractions isolated from GTW were screened in experiments on rats and mice to observe their antifertility effects and found that the monomer T9 among the requirements for male contraceptive need to be elucidated. T9 was administered through gastric intubation at a dose of 0.1mg/kg?d-1 7w? All the T9 treated rats exhibited minimal testicular damage at the end of seventh week of treatment, but causes severe damages mainly the epididymal, the spermatozod showed various structural abnormalities, including cracked midpiece, decapitation of the sperm head commonly ( above 90% ) . It is no malformed round or tadpoleshapes head sperms discernible, no significant changes were seen in main visceral organs, no immunosuppressive actions was observed. The potencies of anti-sperm activity of T9 is 100 times stronger than GTW.