Abstract: Morphology of four sessile peritrichous ciliates from Donghu Lake, including Ophrydium crassicaule Penard, 1922, Pseudovorticella monilata (Tatem, 1870) Foissner & Schiffmann, 1974, Opercularia nutants (Ehrenberg, 1831) Stein, 1854 and an unidentified species Vaginicola sp., were investigated through living observation, protargol staining and silver impregnation. The detailed descriptions of living characters, infraciliature, silverline systems and dimorphic nuclei morphology were presented. These results reinforce the morphology data of peritrichous ciliates, and provide important information to the taxonomy and phylogeny of ciliates. Furthermore, the first report of conjugation process of Pseudovorticella provided the basic knowledge for studying the sexual reproduction of ciliates.