In this study, four filamentous fungi were isolated from dead sheaths of Poaceae in Linzhi, Xizang Autonomous Region, China. Morphological examination and multilocus phylogenetic analysis with the ITS, LSU, SSU, and tef1 loci confirmed the four isolates represent a new species in Periconia, and it is introduced as P. motuoensis. It is characterized by hairy, dark brown to black colonies, apical branched, smooth, thick-walled, solitary, septate conidiophores, light brown and spherical conidiogenous cells, and ellipsoidal to cylindrical, verrucose, thick-walled, sometimes septate and pale brown to brown conidia with two guttulates when mature. Descriptions, illustrations and phylogenetic analysis results of the new species are provided.