Abstract: Nitrogen (N) inputs caused by human activities potentially influences the aquatic environment. However, researches on N pollution in China are mainly discussed from the microscopic point of view, i.e. field experiment. Watershedscale diagnosis of N pollution has just started, leading to ambiguous identification of ecological problems, pollution issues and pollution potential at watershed scale. In this paper, relationships between net anthropogenic N inputs (NANI) and riverine N flux (RNF) and factors influencing these relationships at watershed scale had been investigated. This would help diagnose ecological and environmental problems at watershed scale, understand the roles of natural climate and human activities  in affecting N fluxes, and ultimately provide both theoretical and practical insights into environmental management decisions.