Several environmental variables were monitored water samples were examined from January 2009 to December 2011 to understand the taxonomic structure of coastal phytoplankton communities in Jangmok bay Korea. The phytoplankton community was characterized by identifying and quantifying microalgal taxa in conjunction, also determined Chl a, inorganic nutrients, dissolved oxygen, salinity, temperature and pH. Canonical correspondence analysis (CCA) was used to temporal phytoplankton community changes, and to examine the relationship between species composition and environmental factors. Theses variables were subjected to analysis, to identify correlation. The species diversity of the phytoplankton community changed rapidly, and high species diversity coincided with significantly higher relative diatom abundance, and lower species diversity coincided with significantly higher proportions of phytoplankton taxa other than diatoms and dinoflagellates. In addition, the Chl a concentration was positively correlated to the relative proportion of dinoflagelltes. The relative abundance of some species was dependent on specific environmental variables. Community structure and cell abundance were categorized in relation to monsoon, current and anthropological activities. It is presented that the temperature and hydrodynamics in conjunction with the pattern of nutrients (DIN, DIP and N/P) availability and depletion affect the composharacterized by identifying and quantifying microalgal taxa in conjunction, also determined Chl a, inorganic nutrients, dissolved oxygen, salinity, temperature and pH. Canonical correspondence analysis (CCA) was used to temporal phytoplankton community changes, and to examine the relationship between species composition and environmental factors. Theses variables were subjected to analysis, to identify correlation. The species diversity of the phytoplankton community changed rapidly, and high species diversity coincided with significantly higher relative diatom abundance, and lower species diversity coincided with significantly higher proportions of phytoplankton taxa other than diatoms and dinoflagellates. In addition, the Chl a concentration was positively correlated to the relative proportion of dinoflagelltes. The relative abundance of some species was dependent on specific environmental variables. Community structure and cell abundance were categorized in relation to monsoon, current and anthropological activities. It is presented that the temperature and hydrodynamics in conjunction with the pattern of nutrients (DIN, DIP and N/P) availability and depletion affect the compos