Abstract: This study was conducted to analyze the polymorphisms of ABCG2 gene in Chinese Holstein dairy and aid to provide a theoretical foundation for further research on correlation between ABCG2 gene and milk production performance. The polymorphism of exon9 of ABCG2 gene was detected by PCRSSCP, and the SAS 9.0 was used to analyze the variance between genotypes and milk production performance. The result showed that a single nucleotide change (A/G) in exon9 resulted in the mutation from Tyrosine367 to Cysteine (Y367C) in the ABCG2 (ATP binding cassette, subfamily G, member 2) gene. There were two alleles: A and B, and their allele frequencies were 0.86 and 0.14, respectively. Three genotypes (AA, AB and BB) were found in our materials. The frequency of AA, AB and BB were 0.73, 0.26 and 0.01, respectively. The PIC (Polymorphism Information Content) was 0.22. The milk production performance, individuals with BB genotype were all highest than those with AA and AB genotypes but not significant. The relationship between Y367C and milk production performance was not obviously, but the structure of ABCG2 protein may be influenced by Y367C changed.