The aim of this study was to evaluate, through the use of microsatellite markers, the current genetic diversity and the relationships of 375 individuals from 8 local sheep breeds reared in typical breeding farms in the northwest of China, and moreover, to offer a contribution towards genetic conservation decisions for the studied breeds. The expected heterozygosities and allelic richness for the 8 breeds varied from 0.474 to 0.623 and from 3.8 to 5.4, respectively. All the populations showed a significant deficit in heterozygosity and a relatively low level of genetic diversity. Furthermore, the high positive FIS value (ranging from 0.255 to 0.556) indicated inbreeding to be one of the main causes for high genetic homogeneity and lack of heterozygosity in all breeds. The clustering analysis performed with the DISPAN package showed that Aletai, Kazak, Bashibai and Bayinbuluke were grouped together, and Hetian, Qira black and Duolang were grouped together, which indicated that the relationship among breeds displayed some degree of consistency with their geographical distribution, production and origin. These findings indicate that improved conservation measures must be undertaken to avoid further losses of genetic diversity and minimize inbreeding represented by these breeds.