Abstract: The results of injection of a high molecular copolymer HFMC into vas deferens of male rhesus monkey is preliminarily reported.While HFMC mixed with body fluid in the vas deferens,it immediately polymerized into solid polymer with porosity and attached to the wall of the vas deferens immediately,and released certain amount of H+ gradually,thus the living environment of sperms was changed.In the matching experiment of the rhesus monkey,We could find the difference in fertility resumption,with various dosages of HFMC.In the 30 mg HFMC×2 intra vas deferens group (n=2),the rate of recovered fertility was 100% within 2-5 months,but in 60 mg HFMC×2 intra vas deferens group (n=4) that the rate was only 50% within 2 years of period.Experimental results demonstrated that injection of HFMC induced lethat effects and caused abnormality of sperms and thus obviously decreased sperm vitality.Such effects became stronger and stronger as the dosage of HFMC increased,such influence gradually weakened and disappeared as the length of time after injection of HFMC incrased,the degree of activity of sperms in the semen deterimination were determined by routine methods of WHO that the results analysed was consistent with the results of matching experiment.We are planning to continue the experiment by improvement on the stability of self solubility and the dosage of injection.It is quite possible that HFMC may be a new type of contraceptive for man.