Abstract: The polymorphisms of prolactin receptor (PRLR) gene in four sheep populations (Small Tailed Han, Suffolk, Dorset, F1 of Dorset ♂ crossed with Small Tailed Han ♀) were analyzed by PCR-SSCP. The results indicated that there were three genotypes (AA, AB and BB) detected by three primer pairs. For primer 1, AA genotype was detected in four sheep populations, AB genotype was detected in Small Tailed Han, Suffolk and Dorset sheep, BB genotype was only detected in Dorset sheep. For primer 2, both AA and AB genotypes were detected in four sheep populations, BB genotype was not detected in Suffolk sheep. For primer 3, three genotypes (AA, AB and BB) were detected in four sheep populations. For three primer pairs, frequency of allele A was obviously higher than frequency of allele B in four sheep populations.