In situ observation techniques got rapid development in the process of biological oceanography research, from the physiological and ecological response of marine biodiversity, marine biological and ecological processes of macro and change mechanism and so on, which greatly improved the marine biology, ecology and biogeochemical processes of different temporal and spatial scales. Current techniques including  in situ  optical detection technology, underwater microscopic camera and automatic identification technology, underwater flow cytometry technology, and the biosensor technology based on molecular biology, broaden the study scope of each type of observation platform. This paper will focus on present technology development of  in situ observation of the marine plankton, application and their prospect in the threedimensional ocean observation system.