A new nematode, Cosmocercoides minshan n. sp. (Cosmocercidae) is described from Bufo minshanicus in the Zoige grassland in southwestern China. The new species is characterized as a medium-sized worm (4.93–7.97 mm in length and 0.24–0.47 mm in width), but with a shorter spicule length (0.08–0.21 mm) than other Cosmocercoides, with lateral alae and 9 pairs of caudal papillae. Among the 21 recorded species in this genus, the morphology of the new species is different from all the other species previously reported. DNA sequences of C. minshan sp. showed that the species is almost identical to Cosmocercoides pulcher (99%), and Cosmocercoides tonkinensis (99%). However, there are differences in the morphology and structure of the rosetted papillae among these 3 species, as well as 4 nucleotide differences in the 18S–28S rDNA including the internal transcribed spacer region. In a neighbor-joining phylogenetic tree, C. tonkinensis, C. pulcher, and C. minshan formed a robust clade. Generally, the species is distinguished molecularly and morphologically; thus C. minshan is herein described as a new nematode species of Cosmocercoides.