Abstract: To investigate the effects of N deposition on soil acidification and acid buffering capacity of forestry soil leached by long-term acid rain, a simulated N decomposition experiment was conducted in two typical respective stands of theropencedrymion forest and evergreen broadleaf forest in Jinyun Mountain from April to December 2012. Four N decomposition levels were designed:N0 (0 kg/(hm²·a)), N1 (60 kg/(hm²·a)), N2 (120 kg/(hm²·a)) and N3 (240 kg/(hm²·a)). Samples were collected and analyzed eight months later. The results showed that:1) The lower the soil pH was, the higher acid the buffering capacity gained. 2) Soil acid buffering capacity of the two stands decreased as the amount of N deposition increased. The soil acid buffering capacity of the evergreen broadleaf forest was slightly higher than the theropencedrymion under the same N deposition. 3) N deposition accelerated the rate of soil acidification. Compared with N0, soil pH values of the evergreen broadleaf forest decreased by 0.03,0.06 and 0.16 in N1, N2 and N3, while in theropencedrymion they decreased 0.08,0.10 and 0.26, respectively. 4) Compared with N0, the base cations of the evergreen broadleaf forest were reduced by 55.76%, 66.00% and 70.38% in N1, N2 and N3, respectively, while Al³⁺ increased by 16.03%, 21.37% and 31.81%, respectively. Compared with N0, the base cations of the theropencedrymion forest were reduced by 24.12%, 43.38% and 62.24% in N1, N2 and N3, respectively, while Al³⁺ increased by 19.19%, 23.48% and 34.85%, respectively. The results showed that N deposition decreased acid buffering capacity of the forest soil and accelerated the rate of soil acidification. Evergreen broadleaf forest had a higher susceptibility to N deposition than theropencedrymion.