Abstract: Using a nitrogen budget change model of the Yangtze River basin's agricultural fields, nitrogen budget change in all counties of the Yangtze River basin were counted, while N inputs, outputs and surpluses of the whole basin were obtained. The results indicated that N inputs, outputs and surpluses of the wholebasin in 1990 were 7.65×10⁶, 4.23×10⁶ and 3.42×10⁶ t/a, respectively; among 1990 surpluses, 2.05×10⁶ t/a went into water bodies and 1.37×10⁶t/a remained in the soil. In 2000, N inputs, outputs and surpluses of the wholebasin were 10.22×10⁶, 5.44×10⁶ and 4.78×10⁶ t/a respectively; among 2000 surpluses, 2.65×10⁶ t/a went into water bodies and 2.13×10⁶ t/a remained in the soil. In the Yangtze River basin's agricultural fields from 1990to 2000, changes in N input, output, surpluses, surpluses into water bodies and remaining in soil were 2.57×10⁶, 1.21×10⁶, 1.36×10⁶, 0.60×10⁶ and 0.76×10⁶t/a, respectively. Chongqing, Shanghai, Wuhan, Wuxi, Nanchang and Chengdu, all of which had much more N input into water bodies than other cities from 1990 to 2000, were important prevention and control regions of the Yangtze River basin's agricultural fields.