Abstract: PCRSSCP technology was applied to analyze the polymorphisms of UCP3 gene in 229 beef cattle, including Qinchuan cattle, Qinchuan×Simmental cattle, Qinchuan×Red Angus and Qinchuan× German Yellow cattle. Four genotypes (AA, AB,AC,AD) were identified. The sequencing results showed that genotype AA was the homozygote, genotype AB,AC,AD had mutations C→T(820), G→A(775), G→T(951)， respectively. Statistical analysis indicated that the individuals with genotype AA in slaughter weight, carcass weight, carcass length, eye muscle area, water holding capacity, marbling were higher than those with genotype AB,AC,AD (P＜0.05). The individuals with genotype AB were better than those with AA, AC,AD in backfat thickness( P＜0.05). The conclusion was that genotype AA was a predominant genotype and A was a predominant allele.