Food and agricultural production sector, especially livestock production is vital for Mongolia’s economic and social development. Domestic sheep play key roles for Mongolians, providing food (meat, milk) and raw materials (wool, sheepskin), but genetic diversity, origin of sheep populations in Mongolia have not been well studied. Studies of population genetic diversity is important research field in conservation and restoration of animal breeds and genetic resources. Therefore, this study aimed to investigate genetic characteristics and estimate origin through the analysis of mitochondrial DNA control region D-loop and Cytochrome b of Mongolian indigenous sheep (Mongolian native, Orkhon and Altanbulag) and one Europe sheep (Suffolk). As a result of there were found, 220 SNPs (Single nucleotide polymorphism) in the D-loop region, 28 SNPs in the Cytochrome B region, furthermore, 77 Haplotypes. The nucleotide diversity was only found in D-loop region (n = 0.0184). Phylogenetic analysis showed that 3 (A, B, and C) of 5 haplogroups of sheep have been identified in our research. Haplogroup C was only found in Mongolian indigenous sheep. Haplogroup D and E were not observed. As a result of haplogroups, haplogroup A was dominant (n = 46 of 94 sheeps), followed by haplogroup B (n = 36) and haplogroup C (n = 12). Sequence analysis showed that T deletion, insertion and heteroplasmy in D-loop region occurred at a high rate in Mongolian indigenous sheep population (T insertion = 47, T deletion = 83). The heteroplasmy, which has never been found in Mongolian sheep, has been newly discovered in this study. As a result, the Mongolian sheep varieties, which mainly derived from Asia, were in hybridization with European sheep varieties.