A new species of the genus Gammarus Fabricius, 1775 is described and illustrated from the Tian Shan, China. Gammarus liuruiyui sp. nov. is characterized by eyes being absent; pereopods V-VII bases not expanded; uropod III with scale-like inner ramus, second article of outer ramus vestigial; and posterior margins of epimeral plates nearly straight. Detailed morphological comparisons with related species are discussed. Genetic distances of the new species and related species are provided as proof of the species delimitation.