Abstract: In order to explore the sequence characteristics, expression characteristics and polymorphism of BMPR-ⅠB gene in Tibetan sheep（Ovis aries）on lambing traits, RT-qPCR, clone sequencing, bioinformatics and iMLDR technology were used to detect the tissue expression characteristics of Tibetan sheep BMPR-ⅠB gene, to clone the coding region of Tibetan sheep BMPR-ⅠB gene, to analyze the physicochemical properties and protein structure of BMPR-ⅠB, and to detect polymorphism in Tibetan sheep groups. RT-qPCR results showed that BMPR-ⅠB gene was expressed in 16 tissues including hypothalamus, pituitary, heart, liver, spleen, lung, kidney, ovary, oviduct, uterus, rumen, duodenum, brachial triceps, semitendinosus, quadriceps femoris and longissimus dorsi muscle. The expression level in ovary, oviduct and uterus was higher than the other tissues, and the expression level in muscle tissue was the lowest. Bioinformatics analysis showed that BMPR-ⅠB gene of Tibetan sheep contained an open reading frame with a length of 1 509 bp, encoding 502 amino acids, and the amino acid sequence of the coding region was closest to sheep. The mole-cular formula of BMPR-ⅠB protein was C₂₅₁₁H₃₉₈₆N₆₉₄O₇₄₇S₃₃, the molecular weight was 56 907.45 Da, the total atomic number was 7 971, the theoretical isoelectric point was 7.78, the T_1/2 was 30 h, and the instability index is 54.07. Grand average of hydropathicity（GRAVY）was-0.357; BMPR-ⅠB protein contained signal peptide and one transmembrane region, belonging to transmembrane protein. There were 87 potential phosphorylation sites and 2 N-glycosylation modification sites. The percentage of α-helices,elongation chains, β-turns and random curls were 34.86%, 13.5%, 3.39% and 48.61% respectively.There was A＞G mutation at the FecB site in the coding region of BMPR-ⅠB gene of Tibetan sheep, and there were three genotypes as follows: wild ++ type, heterozygous mutation B+ type and homozygous mutation BB type. The polymorphism information content was 0.07, belonging to low polymorphism, and the locus was in Hardy-Weinberg equilibrium state. The average number of lambs produced by Tibetan sheep differed significantly between genotype ++ and B+（P＜0.05）. The results of this experiment provide reference data for further study on the regulation of BMPR-ⅠB gene on the reproductive performance of Tibetan sheep.