A new species in the subgenus Simulium Latreille s. str. in the genus Simulium is described and illustrated. Simulium（Simulium） sanyaense sp. nov. is from the Sanya District on Hainan Island China. This new species is assigned to the tuberosum-group of the subgenus Simulium and is closely related to Simulium（S.） nitidithorax Puri（1932）, Simulium（S.） brevipar Takaoka and Davies（1995）, Simulium（S.） tianchi Chen, Zhang and Yang（2003）, and Simulium（S.） sigiti Takaoka and Hadi（1991）. However, it is differentiated from them by the genital plate, the enlarged sensory vesicle and the shape of cibarium in the female, and the pupal gill lacking a pit-like cuticular organ.
