Abstract：The PCR-SSCP polymorphism of IGFBP-3 gene exon 3 and Its Correlation with milk yield and growth traits were studied in 105 Holstein cattle and its second backcross generation . The result showed: there were two alleles and three genotypes in the locus of IGFBP-3 gene exon 3. The Allelic frequencies of A and B were 0.7667 and 0.2333 , and the genotypic frequencies of AA, BB and AB were 0.6000, 0.3333 and 0.0667 respectively. The population was at Hardy-Weinberg equilibrium at this locus. The gene heterozygosity and polymorphism information content were listed for 0.3578 and 0.2937 respectively. The sequencing result showed: The B allele had happened a base transformation of G-A at the 8515th bp contrasting with the AF305712, but the A allele has same sequence in here to the AF305712; In addition, there were a no function mutation of T-C for the A and B alleles at the 8634th bp of AF305712. The study by Least Squares Method showed : the milk yield for 305 days and body weight at 12 mouth old of individuals with genotype AA was highly significantly higher than that of individuals with genotype AB and BB respectively (p<0.01). The body length and height at hip cross of individuals with genotype AA was highly significantly higher than that of individuals with genotype AB(p<0.01)，but no significant difference between BB and AB as well as between BB and AA; The genotype did not affected on heart girth and paunch girth significantly.
