In the Three Gorges Reservoir area, 78.1% of precipitation pH was measured below 5.6 by gathering 233 samples of precipitation in 2009-13. The forest ecological system in this area was threatened. In order to quantify the acid risk to the forest ecosystem, acid deposition and nutrient nitrogen critical loads in the area were estimated using simple mass balance equations based on the critical load concept. The values of acid deposition and nutrient nitrogen critical loads varied from 0 to 10.3 keq·ha^-1·yr^-1 and from 0 to 3.5 keq·ha^-1·yr^-1, respectively. Among them, acid critical loads were mostly sensitive to net nitrogen uptake and the ratio of Bc to Al. The accuracy of two parameters improved for reducing the evaluation error of critical loads. And then, exceedance of critical loads was calculated on the basis of critical loads. For the forest soil, exceedance of critical loads were predicted (0-2.1 keq·ha^-1·yr^-1). Acid critical loads were exceeded approximately 4.8% across the entire region, which affected nutrient pools in forested mineral soils. For the forest plants, 20.1% of the forests were predicted to exceed the empirical critical load. In addition, plant species diversity was significantly reduced with the increase of nitrogen deposition. This suggested that forest soil and plants have been adversely affected by acid deposition in some regions of the reservoir area. Thus, the impact of acid deposition on the forest ecosystem can provide key protection regions for the government and a basis for the implementation of emissions reduction policy.