A new species, Didymodon sinicus C. Feng & J. Kou, is described and illustrated based on materials collected from Inner Mongolia, Yunnan and Tibet of China. It is characterized by ovate‐lanceolate to ovate‐triangular leaves that are erect to patent when wet, auriculate leaf base, acute leaves apices, distally bistratose leaf margins, the yellowish color in KOH, short‐excurrent costa with guide cells in 2–3 layers and without ventral stereids, and smooth laminal cells. A phylogenetic analysis based on DNA sequences of ITS, rps4, trnM‐trnV confirms D. sinicus as a sister to the clade of D. obtusus J. Kou, X.‐M. Shao & C. Feng and the new species belongs to the genus Didymodon s.str. [ABSTRACT FROM AUTHOR]