The Black Grouse (Tetrao tetrix) is one of the class Ⅱnational protected birds in China, and its population is declining in recent years. To understand the difference of genetic variation among populations can provide basic knowledge for the conservation of endangered species, and help to develop management strategies. The genetic diversity of two Black Grouse (T.t.baikalensi) populations at Jagdaqi and Zhalantun, Daxinganling of northeast China were analyzed by the polymorphism of mtDNA D-loop sequences. 118 complete sequences were determined using DNA sequencing technology. 25 polymorphic sites, and 33 haplotypes were defined, of which 4 haplotypes were shared between two populations. The nucleotide diversity(π)of Black Grouse in Jagdaqi and Zhalantun populations were 0.279% and 0.191% respectively, with higher polymorphism in Jagdaqi population. The average number of nucleotide difference (K) and the nucleotide diversity(π)were 2.608 and 0.228% in integral population. There was gene exchange between the two populations(N_m=14.63), and their genetic divergence was not significant. The estimate of Tajima's D and Fu&Li's D didn't deviate significantly from the neutral selection hypothesis(P>0.1)for the two populations, suggesting that they might not have been large-scale population expansion process.