Abstract: Abstract: Taimen (Hucho taimen) is a native fish species in China and it is in the state of endangerment. To explain clearly the genetic diversity and genetic structure, 9 wild populations of taimen were investigated using 20 microsatellite markers. The results showed that their observed heterozygosity ranged from 0.0994 to 0.8882, the expected heterozygosity varied from 0.2005 to 0.8759, and the range of PIC index was from 0.3432 to 0.5261 while population from Huma River had low genetic diversity. Fst of matching group ranged from 0.0246 to 0.2333 (P<0.0001)and Nm varied among 0.8216 to 9.9292, which indicated that the genetic differentiation was remarkable among populations.The half/full-sib family tests detected a proportion of half/full-sib family groups varying among 27.78% to 90.91%, showing a high inbred pressure and a risk ofbottlenecks experienced by most groups. The AMOVA results showed that the global Fst was 0.1081; the clustering result showed that individuals from Beiji tributary of Heilongjiang River clustered as one clade, all individuals from Huma River and Wusuli River clustered as one clade and all individuals from the upper reaches of the Heilongjiang River clustered as another clade. All these results indicated that the decrease of taimen resource has affected the gene exchange among their populations. In order to achieve full protection of taimen germplasm resources, we should put an end to the destructive fishing for taimen and promotegene exchange among their populations.