Nitrogen in watershed not only contributes significantly to ecosystem services, but also easily causes ecological and environmental damage, which has attracted extensive attention of watershed researchers. This study integrates the results of previous studies on different aspects of watershed nitrogen, which is of great significance for sorting out the research status, clarifying research hotspots and predicting research trends in this field, and helps to clarify key theories and technologies for improving the above-mentioned ecological and environmental problems. As a new literature analysis method, scientific mapping effectively makes up for the shortage of limited references and only qualitative induction in traditional literature review. Quantitative analysis of scientific literature published from 2000—2019 by scientific mapping is based on the core collection of Web of Science as data source. The research progress in the field of nitrogen of watershed is systematically reviewed from the number of papers and distribution of journals, international and institutional cooperation, interdisciplinary, research themes and evolution. For number of papers and distribution of journals, number of papers published is increasing annually, journals with high production of papers include Science of the Total Environment, Biogeochemistry and Journal of Hydrology. For nation’s cooperation, China and U.S. have the largest number of publications and it is strengthening the power of international co-operation; For institution’s cooperation, the Chinese Academy of Sciences and the U.S. Geological Survey have issued the largest number of publications, and they are leading forces of institutional cooperation in recent and previous periods. For interdisciplinary, nitrogen of watershed shows multi-disciplinarily characteristics. Key disciplines include environmental, water resources science, and geology. For research themes and evolution, nitrogen of forms and transformations, nutrients and eutrophication, water quality and management are critical of research in field of nitrogen of watershed; future research hotspots include distribution characteristics of nitrogen in watershed driven by anthropogenic and climate change, application of models and best management practices in basin management. Future studies should focus on the driving mechanism of watershed nitrogen dynamics and optimization of nitrogen management, quantify hydrological characteristics such as runoff under the background of climate change, and impact of land use type transition driven by human activities such as urbanization and agricultural development on regional nitrogen cycle and load, construct a nature-based management scheme based on the theory of country's mountains, rivers, forests, land and lakes form a community of shared life, and evaluate watershed ecosystem services, including provisioning services (e.g., drinking water and food), regulating services (e.g., water purification and flood control), cultural services (e.g., tourism revenue and natural heritage), and supporting services (e.g., biodiversity maintenance), provided by management measures.