Abstract: In order to understand the relationship between exon polymorphisms of the insulin-like growth factor 1 receptor（IGF1R） gene and weight and body size traits in Kunming dogs, so as to find reliable molecular selection markers for the breeding of high-quality Kunming dogs, in the experiment, the single nucleotide polymorphism（SNP） loci in the exonic region of Kunming dog IGF1R gene were screened by PCR-single strand conformation polymorphism（PCR-SSCP）. The mutation status was analyzed by sequencing, and dominant genotypes, dominant alleles, polymorphic information content（PIC） homozygosity（Ho）, heterozygosity（He）, number of effective alleles（Ne） and Hardy-Weinberg equilibrium status of SNP loci were counted. Finally, general linear model was used to analyze the association between SNP loci and body weight and body size traits in Kunming dogs. The results showed that only one SNP locus was recognized in the exon of Kunming dog IGF1R gene; the site was located at nucleotide 1 773 of exon 8, with a point mutation of C→T but no change in amino acid, and was named C1773T locus. There were two genotypes of the C1773T locus in the Kunming dog population, CC homozygotic type and CT heterozygous type, in which the dominant genotype was CC homozygotic type and the dominant allele was C, which showed a low degree of polymorphism（PIC＜0.25）; Ho was 0.97; He was 0.03, and Ne was 1.03, which was in Hardy-Weinberg equilibrium in the Kunming dog population. The chest width of CC homozygotic type individuals was significantly higher than that of CT heterozygous individuals in the C1773T locus of the IGF1R gene in Kunming dogs（P＜0.05）; the differences in other physical traits were not significant（P＞0.05）. The results indicated that the C1773T locus of the IGF1R gene had a certain effect on the chest width of Kunming dogs, which could be used as a potential molecular selection marker for Kunming dog breeding.