Abstract: The Q249R mutation (A746G) in bone morphogenetic protein receptor-ⅠB (BMPR-ⅠB) is associated with the high prolificacy of Booroola Merino sheep. In our previous study, we found that, in Small Tailed Han sheep population, a high proportion of ewes carry such mutation. The present study further analyzed the polymorphism, effect and linkage of BMPR-ⅠB gene in this breed. The results indicated that the genotype frequencies of BB, B+ and ++ were 0.541 8, 0.364 5 and 0.093 7 respectively, and the allelic frequency of B was 0.724 1.The substitution effect and dominance effect of the B allele were estimated to be 0.46 and 0.16 for the first parity and 0.56 and 0.11 for the second parity, respectively. Moreover, the fully FecB-associated microsatellite marker OARJL36 was genotyped in the BB ewes of Small Tailed Han sheep. We found that, in Small Tailed Han sheep, recombination between BMPR-ⅠB gene and OARJL36 locus are still occurring.