Hydrological and biogeochemical cycles process in a watershed ecosystem are closely coupled by the physical function of the hydrological flux, of which the coupling process of the matter and energy in the spatial and temporal scales will provide important basis for matter balance in biogeochemical cycles. These cycles also influence ecosystem productivity and exchanges with the atmosphere and the downstream water bodies. Therefore, the research on biogeochemical cycle and hydrological coupling process in the watershed scale will reveal the coupling mechanism on the carbon-nitrogen coupling cycles between terrestrial and aquatic ecosystem under water cycle driving, and the interaction of human activities and associated biological, physical and chemical processes under climatic change. The aims of this study are to synthetically clarify the biogeochemical and hydrological coupling characteristics in temporal, spatial and spatio-temporal scales within a watershed ecosystem, reveal the coupling of nutrient cycling in spatio- temporal scales within a continuum of atmosphere- land- riversestuaries- marine systems, which are connected by water, gas and aerosol fluxes; disclose the biological regulation mechanism of the biogeochemical and hydrological coupling processes by the change of ecological stoichiometry characteristics within the watershed and the regulation of nutrient input and output by water- land interaction zone, and then finally enhance our understanding of ecohydrological and biogeochemical process and its ecological dynamics at watershed landscape scale.