Abstract: The characteristics of vertical profiles and seasonal variations of biogenic elements in the Huanghai Sea Cold Water Mass (HSCWM) are discussed based on the field data of the project China-Korea Joint Research on the Seawater Circulation and Mass Flux in the Huanghai Sea.The results show that nutrients are generally depleted by phytoplankton in the upper layer,but enriched in the depth below pycnocline rather than the euphotic zone throughorganism decomposition during the stratified period in the HSCWM.The stratification is also very obvious in vertical profiles of dissolved oxygen,pH and chlorophyll,with high content in the upper layer and low content in the lowerlayer.The maximum values occur in the middle layer (20～30 m) for DO in the period from May to October andpH in May and July,which are resulted from the coaction of thermocline and intensive photosynthesis due to subsurface chlorophyll maximum in the same layer.The factors influencing the content and distributions of biogenic elements and their interrelationships are also discussed and analyzed.