Abstract: 【Objective】 The objective of this study was to discuss the genetic differnation and the isolation mechanism by distance of some different ecological type sheep breeds in Mongolia Group. 【Method】 Five populations including Hu sheep, Tong sheep, small-tailed Han sheep, Tan sheep and Wadi sheep were determined electrophoetically and iondensitometrically the constitution of allele frequencies at twenty blood protein and no-protein loci (Al, Gc, Tf, Cp, Alp, Ary-Es, Lap, Hb-α, Hb-β, Xp, CA, Dia-I, Dia-Ⅱ, MDH, GPI, EsD,α2-M, Cat, Ly and Ke ); 【Result】 The phylogenetic relationships of five sheep populations in this study did not meet the mechanism of isolation by distance , and the genetic differentiation relationships among 5 sheep populations were not closely linearly correlative with their geography distribution; 【Conclusion】 The findings supported the related records in literature,the five populations originated on different time stage from the primogenitor population and communicated genetically with each other thereafter in the process of natural and artificial selection and on different ecological environment.

Key words: mongolia sheep group, different ecological type, genetic differentiation, isolation by distance