Abstract: A total of 676 pigs including 62 Wei pigs, 64 Landrace pigs, 61 Duroc pigs, 60 British Large Yorkshire pigs, 65 Changwei pigs of the zero generation, 121 Changwei pigs of the first generation; and 243 Changwei pigs of the second generation were selected. Distribution of Hal gene genotypes was detected by PCR-RFLP. In the detected swine breeds, the frequency of dominate homozygote of Hal gene was 1.00, 0.71, 0.80, 0.62, 0.91, 0.88 and 0.82, respectively. The frequency of heterozygote was 0, 0.29, 0.20, 0.37, 0.09, 0.12 and 0.18, respectively. Although the allele frequency and genotype frequency of halothane sensitive gene were low in the Changwei pigs of the three generations, the allele frequency of Hal and the genotype frequency of HalN Haln showed a rising trend in the three generations. As a result, the marker-assisted selection should be adopted to reduce the gene frequency of Haln until it is eliminated entirely.