Radula hainanensis L.N.Zhang & R.L.Zhu sp. nov. (Radulaceae), a new species from Hainan Island of China, is described and illustrated. This species can be recognized by the presence of gemmae at the apical and dorsal margins of leaf-lobes on ascending to erect shoots, the thin-walled leaf cells with triradiate trigones, and the occurrence of two different types of oil bodies within each leaf-lobe cell. It is superficially similar to Radula constricta, a common species in East Asia, which differs in having larger leaf-lobules 1/2–2/3 as long as the leaf-lobes, only one type of oil body within each leaf-lobe cell, and absence of ascending to erect gemmiferous shoots.