A three-dimensional model coupled with a four-component (NPZD) low trophic model is applied to the East Sea, focusing on ecosystem responses to upwelling environment near the Korean coast. The physical model is based on the Regional Ocean Model System (ROMS). The biological model was initialized with horizontally-uniform vertical profiles of N, P, Z and D. Reproduced chlorophyll features such as chlorophyll filaments and chlorophyll eddy are similar with ocean physical features of the East Sea, and agree well with Geostationary Ocean Color Image (GOCI) of Korea Ocean Satellite Center (KOSE). Our simulation shows that, during heating season, the coastal upwelling near the Korean coast largely controls ecosystem evolution and subsurface chlorophyll maximum (SCM) in this area is reproduced near the thermocline with appropriate spatial scales and tends to deepen toward the open ocean, compared with previous studies. During cooling the SCM disappears and chlorophyll is well mixed in the upper ocean.odel System (ROMS). The biological model was initialized with horizontally-uniform vertical profiles of N, P, Z and D. Reproduced chlorophyll features such as chlorophyll filaments and chlorophyll eddy are similar with ocean physical features of the East Sea, and agree well with Geostationary Ocean Color Image (GOCI) of Korea Ocean Satellite Center (KOSE). Our simulation shows that, during heating season, the coastal upwelling near the Korean coast largely controls ecosystem evolution and subsurface chlorophyll maximum (SCM) in this area is reproduced near the thermocline with appropriate spatial scales and tends to deepen toward the open ocean, compared with previous studies. During cooling the SCM disappears and chlorophyll is well mixed in the upper ocean.