Abstract: Free-living scuticociliates are common inhabitants of littoral and sandy habitats, some of which are faculta?tive histophagous parasites in marine fish. Therefore, it is very important to recognize and study those ciliates. However, the distribution, especially in South China Sea and the species inventory of this group are still limited. This study aims to supply new information to this group from both the northern and southern China seas. Eight marine scuticociliates: Pleuronema coronatum Kent, 1881, Pleuronema wiackowskii Wang et al., 2008, Cohnilembus verminus Mller, 1786, Miamiensis avidus Thompson Moewus, 1964, Uronema heteromarinum Pan et al., 2010, Metanophrys sinensis Song Wilbert, 2000 and two species of Mesanophrys cf. carcini, were morphologically investigated by using live observa-tion, portargol impregnation and silver nitrate impregnation methods. Pleuronema wiackowskii, the new record for the South China Sea, had wider ranges of body size and higher number of somatic kineties than the original Qingdao popu-lation. Uronema heteromarinum, the population obtained from the South China Sea, was similar to the Qingdao population reported by Pan et al. (2010). Metanophrys sinensis, obtained from an aquafarm of Weifang, Shandong Province, deferred from previous investigations in body size and the number of somatic kineties. The population of Miamiensis avidus, also obtained from the same aquafarm, had stable 12 somatic kineties, which was different from the reports of Thompson Moewus (1964) (10-13), Dragesco et al. (1995) (13-14) and Song Wilbert (2000) (13-15). Two forms of Mesanophrys, collected from coastal area of Qingdao and Hongkong respectively, owned stable number of somatic kineties, which were different from the well-konwn Mesanophrys carcini. Considering this insufficient evidence they were defined as Mesanophrys cf. carcini preliminarily. The populations of Pleuronema coronatum and Cohnilembus verminus, which respectively collected from the coastal water of Guangdong and the aquafarm of Weifang, corresponded well with previous investigations.