Abstract: PCR-RFLP technique was used to analyze the polymorphisms of CSN1S2^F loci in 69 Xinong Saanen dairy goats. 310 bp fragment of CSN1S2^F gene digested with Alw26I demonstrated polymorphisms, namely, allele F with only one 310 bp band and allele N with 179 bp, 131 bp bands. Correspondingly, it showed that genotype FF of individuals had 310 bp band, genotype NF of individuals had 310 bp, 179 bp and 131 bp bands, and genotype NN of individual had 179 bp and 131 bp bands. In this Xinong Saanen goat population, gene frequencies of allele F and N were 0.087 0 and 0.913 0, respectively, which was at HardyWeinberg equilibrium (P＞0.05). Analyzing correlation between different genotypes of CSN1S2 gene and average milk yield, we could find that different genotypes had significantly effect on average milk yield. In average milk yield index, milk yield of individual with genotype NN was the highest, and genotype NN were prior to FF genotype (P＜0.05). Association different genotypes of CSN1S2 gene with body size indexes indicated that individual with genotype NF was better than those of genotype NN in body weight and stature (P＜0.05), and individuals with genotypes NF and NN had no significant difference in other indexes (P＞0.05), such as body size, shank girth and body weight.