At present, most species of Hercostomus were divided into 25 species groups in China. In this paper, we proposed a new species group, the Hercostomus furcatus group, on the basis of the black body and legs, the yellow middle and lower postocular bristles, and the furcated cercus with distinct marginal denticles. Here one new species, Hercostomus liangi sp. n., from China and it is described as new to science. A key to species groups of Hercostomus is provided.