The Music Frog genus Nidirana was recently resurrected as a distinct genus and contains 14 species distributed in subtropical eastern and southeastern Asia. The species diversity of Nidirana is dramatically underestimated, and half of its species was described in the last five years. In this study, Nidirana occidentalis sp. nov., a new species of Music Frog from western Yunnan, China, is proposed based on morphological and molecular evidences. The new species was previously misidentified as N. pleuraden, but can be distinguished from the true N. pleuraden from eastern Yunnan, and all other congeners, by a combination of morphological characteristics, and significant divergence in the mitochondrial genes (≥ 5.1% in 16S and ≥ 8.9% in CO1). Nidirana occidentalis sp. nov. is assigned to the N. pleuraden group on the basis of morphological characters, but its phylogenetic placement remains unresolved due to weak branch support. Geographically, these two species are isolated by the Red River in Yunnan, supporting the hypothesis that the Red River is an important geographical barrier that drives speciation in flora and fauna. Nidirana occidentalis sp. nov. represents the second species of N. pleuraden group and the 15th species of the genus.