Abstract: For exploring the molecular mechanism of prolificacy and providing theoretical basis for marker-assisted selection and breeding of fecundity in sheep. PCR-SSCP was used to detect polymorphism of BMPR-IB gene Exon7 for five sheep breeds (Texel Sheep, Poll Dorset Sheep, Germany Merino Sheep, Small Tail Han Sheep, Tibetan Sheep) with different fertility. The results showed that AA and AB genotypes were found in five groups. The sequencing analysis indicated that AB genotype was C→T mutation in coding region of 846 and existed the heterozygous of C/T. Genotype AA was dominant genotype and allele A was dominant allele in five sheep breeds. The PIC of Texel Sheep, Poll Dorset Sheep and Germany Merino Sheep was between 0.25 to 0.5 and they were moderately polymorphic by population genetics, Small Tail Han Sheep and Tibetan Sheep were low polymorphism (PIC<0.25). In addition to the Texel Sheep, the other sheep breeds were in Hardy-weinberg equilibrium by χ2 test. This mutation point distributions had differences in different prolificacy sheep groups by significant test. Germany Merino Sheep had no significant differences with Texel Sheep and Poll Dorset Sheep (P>0.05), Small Tail Han Sheep had significant differences with Texel Sheep and Poll Dorset Sheep (0.010.05). This mutation could be considered as a potential locus to control reproduction of sheep.