Abstract: Tan sheep is an excellent local sheep breed in China.Investigating the correlation between microsatellite marker and body weight trait is conducive to establish the molecular marker-based novel breeding system for Tan sheep.In this study,the polymorphisms of 12 microsatellite loci,including BL1080,BM6506,BM7145,BMS2263,BMS678,ILSTS004,ILSTS30,MCM58,BMS1591,BMS1636,CSSM004 and MCM130 which were closely linked to the major genes associated with weight trait in sheep,were detected in 51 ewes of Tan sheep.The PCR amplified products of the microsatellite loci were detected by agarose gel electrophoresis.The allele frequency,polymorphism information content,gene homogeneity and heterozygosity of the 12 microsatellite loci were calculated.The results demonstrated that the 12 selected microsatellite markers were all highly polymorphic loci;the microsatellite locus BMS1636 had the highest polymorphism among the 12 tested microsatellite loci,while the microsatellite locus BL1080 showed the lowest polymorphism.These results provide basic molecular data for the research on the germplasm characteristics of Tan sheep.