706 pigs were detected the recessive halothane recessive alleles(Haln) with HhaI restriction enzyme by PCR-RFLP,which included 261 Yorkshire,265 Landrace,140 Duroc and 40 Huai.The results showed that the genotypes of all pigs were NN,without Nn and nn,and there had been almost no pigs carrying Haln regardless of breed.This information was provided for selecting seed breeding pigs,and theory base for reservation and development of Huai pigs.