The Sanjiangyuan region of Qinghai-Tibetan Plateau is recognized as a biodiversity hotspot of alpine mammals but a barren area in terms of amphibians and reptiles. Here, we describe a new pit viper species, Gloydius rubromaculatus sp. n. Shi, Li and Liu, 2017 that was discovered in this region, with a brief taxonomic revision of the genus Gloydius. The new species can be distinguished from the other congeneric species by the following characteristics: cardinal crossbands on the back, indistinct canthus rostralis, glossy dorsal scales, colubrid-like oval head shape, irregular small black spots on the head scales, black eyes and high altitude distribution (3300-4770 m above sea level). The mitochondrial phylogenetic reconstruction supported the validity of the new species and furthermore reaffirms that G. intermedius changdaoensis, G. halys cognatus, G. h. caraganus and G. h. stejnegeri should be elevated as full species. Gloydius rubromaculatus sp. n. was found to be insectivorous: preying on moths (Lepidoptera, Noctuidae, Sideridis sp.) in the wild. This unusual diet may be one of the key factors to the survival of this species in such a harsh alpine environment.