Paracalanus parvus(Clans) is one of the dominant species of the Pelagic copepods found in liaozhou Bay. This paper presents the results of studies made on copepodid stage morphology of it, a detailed morphological description as well as figures of its five copepodid stages are given. The sex of this species begin to differentiate when it reaches stage IE. Peroioped I of the copepodid of each stage has no apical spine from which itcan be distinguished from its allied species--Paracalanus crassirostris Dahl as well asfrom adult. The material for study was collected in 1982. The length of the individual in winter-spring is larger than that in summer-autumn. It is worthy of note that no matter in what season the sample was collected, the length of copepodid I-Y is constantly 1.3 times that of the metasome.