The Tuojiang River basin in Sichuan Province is polluted by total nitrogen from non-point sources. Livestock breeding is the main contributor to this pollution, while rural life and domestic waste have decreased. Farmland solid waste and runoff have increased. Overall, the total nitrogen pollution load has decreased from 2007 to 2017. The pollution centers of gravity have shifted from northwest to southeast due to spatial heterogeneity and rainfall runoff. The key area for prevention and control of pollution sources is in the southeast of the watershed. The research findings help in improving the aquatic environment and promoting sustainable development in the Tuojiang River basin.