Begonia scorpiuroloba sp. nov., a new species in Begonia sect. Platycentrum (Begoniaceae) from southern Guangxi of China, is described and illustrated. Morphologically, it is mostly similar to B. pedatifida, but differs clearly by its narrower lobes, denser hairs on leaf surface, obtuse angle of leaf base, subequal tepals of female flowers and late flowering. This new species is endemic to Guangxi and is assigned to Endangered (EN) according to the IUCN Red List Categories and Criteria.