A new leporid species, Nesolagus sinensis sp. nov., is described here representing the only leporid member of the Early Pleistocene Gigantopithecus fauna from Sanhe Cave, Chongzuo, Guangxi, South China and also the first fossil taxon of the Southeast Asian genus Nesolagus. Compared with two extant Nesolagus species from Indonesia and Vietnam and other related leprids, the new species has a relatively small size and an extraordinarily weak anterior internal reentrant (AIR) on p3, but it also retains the simplified paedomorphic pattern during the ontogenetic process as in extant species, which suggests that the new species is more primitive than and probably directly ancestral to extant Nesolagus species. The new species seems closely related to Alilepus longisinuosus from the Late Miocene strata of Lufeng, Yunnan, and probably diverged from a leporid similar to its ancestral form. It also indicates that Nesolagus originated in Southwest China. A new leporid species, Nesolagus sinensis sp. Nov., Is described here representing the only leporid member of the Early Pleistocene Gigantopithecus fauna from Sanhe Cave, Chongzuo, Guangxi, South China and also the first fossil taxon of the Southeast Asian genus Nesolagus. with two extant Nesolagus species from Indonesia and Vietnam and other related leprids, the new species has a relatively small size and an extraordinarily weak anterior internal reentrant (AIR) on p3, but it also retains the simplified paedomorphic pattern during the ontogenetic process as in extant species, which suggests that the new species is more primitive than and probably directly ancestral to extant Nesolagus species. The new species seems closely related to Alilepus longisinuosus from the Late Miocene strata of Lufeng, Yunnan, and probably diverged from a leporid similar to its ancestral form also It said that Nesolagus originated in Southwest China.