Abstract: The genetic diversity of three sheep breeds and two crossbreeds was surveyed using 7 microsatellite loci. The five breeds include Polled Dorset sheep, Tan sheep, Small Tail Han sheep, the Crossbreed of Tan sheep and Small Tail Han sheep, the Crossbreed of Polled Dorset sheep and the Crossbreed of Tan sheep and Small Tail Han sheep. The 7 microsatellite loci showed high polymorphism information content value. The mean polymorphism information content value was between 0.7077 and 0.8396, which indicated that the 5 breeds had abundant genetic diversity. The mean heterozygosity was between 0.7454 and 0.8665. In the UPGMA dendrogram and NJ based on the Nei genetic distance, Tan sheep and the Crossbreed of Tan sheep and Small Tail Han sheep had the intimate relationship, Small Tail Han sheep and the Crossbreed of Polled Dorset sheep the Crossbreed of Tan sheep and Small Tail sheep had close relationship, which were classified as one sort. But Tan sheep and Small Tail sheep had distant relationship with Polled Dorset sheep.

Key words: sheep; microsatellite; polymorphism information content (PIC); genetic diversity; Nei genetic distance