Abstract: 30 healthy 180-day-old Jingbei 939 cocks were divided into two groups randomly, 15 cocks each.Every cock was fed with the same full-nutrition-proportioned feed in a respective cage. The control group was provided with tap water, while the experimental group was given tap water with 3 000 mg/L NaF. Experiment last for 70 days. On the 70th day, all the cocks were killed, and the ratio of testicle to weight were measured one by one. The testicle tissue was collected and observed by general pathology and ultramicropathology. The results showed that the high fluorine can sharply lower weight of testicle and body, and made serious damages to seminiferous tubule, spermatogenic cell and interstitial cell. This research proved that the high fluorine can hurt cock’s procreative function seriously.