Abstract: Species composition, distribution, fauna similarity and threatened factors of freshwater molluscks in the Gan River Basin were analyzed based on the systematic investigation from 2016 to 2017. In addition, we also provided some strategies to protect freshwater molluscks. The results showed that 62 species of freshwater molluscks were identified, belonged to 29 genera, 14 families and 2 classes, and included a new record species-Lithoglyphopsis ovatus. Among which that 29 species belonged to 16 genera and 11 families of Gastropoda, 33 species belonged to 13 genera and 3 families of Bivalvia. There were 27 endemic species to China(Gastropoda had 6 species and Bivalvia had 21 species), and 23 threatened species to China(Gastropoda had 4 species and Bivalvia had 19 species). From the frequency of occurrence of species, Corbicula fluminea, Limnoperna lacustris, Unio douglasiae, Anodonta woodiana woodiana, Bellamya aeruginosa, Bellamya purificata and Pomacea canaliculata were widely distributed in the Gan River Basin. From the perspective of fauna similarity analysis, distribution of freshwater molluscks between the main stem and tributary of the Gan River Basin was significantly different, and species richness of the main stem was higher than tributary. Due to the effect of human activities, especially sand mining, water pollution and overharvesting, freshwater molluscks resources in the Gan River Basin had declined rapidly, which should attract much attention and strengthen protection.