NR5A2 has been implicated in processes as diverse as steroidogenesis, cellular proliferation, ovarian follicular development, ovulation, and fertility in mammals. However, data about the relationship between NR5A2 and prolificacy in mammals are lacking. In the present study, we identified and characterized NR5A2 of Hu sheep, and investigated the correlation between NR5A2 and reproductive performance. The full-length coding region was 1488 bp, and the gene was conserved in mammals. We found a positive correlation between NR5A2 mRNA levels in the ovary and the ovulation rate and litter size of Hu sheep. We detected two single nucleotide polymorphisms (T40C and T1419C) in the coding sequence of NR5A2. At the third and average parity, litter size of Hu ewes with CC genotype at T40C locus was larger than those of ewes with TT or TC genotypes; at the T1419C locus, Hu ewes with TT genotype was greater than those of ewes with CC genotype at the third parity. Our findings demonstrated that NR5A2 was associated with reproductive performance in Hu sheep, a high prolificacy breed.