[in Chinese with English abstract and description of a new taxon] The lichen-forming genus Diploschistes belongs to Ascomycota, Lecanoromycetes, Ostropomycetidae, Graphidales, Diploschistaceae. This genus includes 48 crustose species worldwide, and is confirmed as monophyletic group. Based on morphological, anatomical and chemical observation combined with phylogenetic analysis of ITS, a new species of Diploschistes, D. viridis (referring to subg. Diploschistes), is found and described from western Tianshan Mountains. Detailed morphological descriptions, illustrations, habitat and color photos of this species are provided, and an ITS phylogenetic tree was constructed by maximum likelihood (ML) and Bayesian inference (BI) method. Keywords: Diploschistes; urceolate apothecia; phylogeny; monophyletic; lecanoric acid.