The mammalian Y chromosome plays a critical role in spermatogenesis. However, the exact functions of each gene on the Y chromosome have not been completely elucidated, due, in part, to difficulties in gene targeting analysis of the Y chromosome. The zinc finger protein, Y-linked (ZFY) gene was first proposed to be a sex determination factor, although its function in spermatogenesis has recently been elucidated. Nevertheless, ZFY gene targeting analysis has not been performed to date. In the present study, RNA interference (RNAi) was used to generate ZFY-interrupted Hu sheep by injecting short hairpin RNA (shRNA) into round spermatids. The resulting spermatozoa exhibited abnormal sperm morphology, including spermatozoa without tails and others with head and tail abnormalities. Quantitative real-time polymerase chain reaction analysis showed that ZFY mRNA expression was decreased significantly in Hu sheep with interrupted ZFY compared with wild-type Hu sheep. The sex ratio of lambs also exhibited a bias towards females. Together, the experimental strategy and findings of the present study reveal that ZFY also functions in spermatogenesis in Hu sheep and facilitate the use of RNAi in the control of sex in Hu sheep.