We describe a new species (Sinospelaeobdella jiangxiensissp. n.) from a natural cave in southwestern Jiangxi Province, China, according to external and internal morphology and COI gene sequences. S. jiangxiensissp. n. is distinguishable from other species of Sinospelaeobdella primarily by morphological characteristics, including body length, the position of the fifth pair of eyes and the first pair of testes, the number of caeca, and the shape and number of auricular projections. We also estimate its phylogenetic position within the genus Sinospelaeobdella. Molecular phylogenetic analyses supported the morphological delimitation of S. jiangxiensissp. n. as separate from S. wulingensis. Both the morphological and molecular data support S. jiangxiensissp. n. as a new species, so the results provide critical data for the determination and conservation of Sinospelaeobdella, and enhance the documented diversity of this recently established genus.