Based on samples collected with CTD water sampler at a depth of 5 m  from 18 sites in southern South China Sea during later autumn

2013， species composition and abundance of planktonic ciliate and its relationship with the environment variables were investigated. A total 17 species belonging to 10 genera and two orders (Tintinnida and Oligotrichida) were identified. Among them

there were five dominant species (dominance Y≥002)

including Rhabdonella sanyahensis

Strombidium conicum

Eutintinnus stramentus

Codonellopsis morchella

Strombidium globosaneum. The mean abundance of ciliate was (36.5±3.8) ind./L (10~80 ind./L). Ciliates abundance distribution presents a patchy distribution

and the distribution of planktonic ciliates may be closely related to ocean circulation. Canonical correspondence analysis demonstrated that the nutrient level and Chlorophyll a concentration were the most important factors affecting the spatial pattern of planktonic ciliate communities in southern South China Sea.