Single nucleotide polymorphisms of exon 5 T32207C and exon 7 A35230G of integrin β1 gene were detected in Landrace, Large White and Duroc by CRS-RFLP. Association between the polymorphism and litter size was analyzed by the method of least square means. At 32207 polymorphic loci, there was no significant difference on TNB and NBA between the genotypes in Landrace, Large White, and Duroc. At 35230 polymorphic loci, there was significant difference (P<0.05) or greatly significant difference (P<0.01) on TNB and NBA between genotypes in the first, second, and all parities in Large White and Landrace. The effects of GG and AG genotypes were different from that of AA genotypes with the order of GG, AG>AA. These results suggested that the effect of G allele of integrin β1 gene on litter size is significant in Large White and Landrace.