A total of 158 pigs of Yorkshire, Landrace and Duroc were selected from some swine breeding farms in Hunan province. The genotypes of enterotoxigenic E.coli F18 receptor were tested by PCR-RFLP. The results showed that the frequency of resistant genotype AA was 0.11,the frequencies of susceptibility genotype AG and GG were 0.35 and 0.54 respectively.