The full characterized list of known species of Harpacticoida is presented for the South China Sea based on original and literature data. Three Harpacticoida taxocenes from soft sediments are described on the littoral and sublittoral of shallows of Nha Trang Bay (Vietnam). The first taxocene is represented by dominating species of the genuses Phyllopodopsyllus and Brianola at the upper and middle littorals. The second one, which is characterized by dominating species of the genus Diarthrodes, is found on sublittoral, silty and fine sands. The third taxocene with dominating species of the genus Amphiascoides is described at coarse sands. The sediment type is a main factor of the organization of sublittoral harpacticoids associations. The depth also has an effect on the harpacticoids diversity and abundance. A comparative analysis of the Harpacticoida species composition is presented for the South China Sea, the Philippines, the Malay Archipelago, New Guinea, the Yellow Sea, and the Andaman and Nicobar Islands. The similarity of the species lists of the considered sector of the Indo-Pacific is extremely low. The main reason for the present high specificity of the faunas of the compared regions is the deficit of studies on Harpacticoida in tropical waters.