Abstract: 【Objective】 Forecast of the heterosis of Small Tail Han Sheep crossed with imported meat sheep by genetic polymorphism of microsatellite DNA was made in different sheep breeds. 【Method】Gene frequency, polymorphism information contents, number of effective alleles, heterozygosity and genetic distances were studied in four imported meat sheep and Small Tail Han Sheep using five microsatellite loci. The crossing effects on Small Tail Han Sheep with four imported meat sheep were tested.【Result】The results indicate that there are genetic polymorphisms at five microsatellite loci in five sheep breeds. Five microsatellite loci can be used for genetic diversity evaluation in sheep breeds. The genetic variability of Dorset is the highest, and Small Tail Han Sheep is the lowest in five sheep breeds. The order of heterosis from large to small in four imported meat sheep by the analysis of genetic relationship is White-Suffolk, Black-Suffolk, Dorset, Texel. It accords with testing results on actual heterosis. 【Conclusion】It is feasible to forecast the heterosis of Small Tail Han Sheep crossed with imported meat sheep by genetic polymorphism of microsatellite DNA and it will have an important value for sheep breeding in future.

Key words: sheep, microsatellite DNA, genetic polymorphism, heterosis