Human activities have caused increased nitrogen (N) input to forest ecosystems through fertilizer production and fossil fuel combustion in recent decades and this input is likely to continue in the near future. Therefore, studying the effects of N deposition on morphological and physiological characteristics of plants increasingly becomes a major focus in the field of ecological and environmental sciences. To explore physiological response of sub-tropical forest to N deposition, Schima superba was selected as an important constructive species of sub-tropical forest. Four treatments including Control (CK, 0 kg N hm^-2·a^-1), Low N (LN, 50 kg N hm^-2·a^-1), Medium N (MN, 100 kg N hm^-2·a^-1) and High N (HN, 150 kg N hm^-2·a^-1) were conducted in the present study. At the beginning and in the middle of each month, N-treated plots were sprayed with NH₄NO₃ solution with concentrations of 0 mol N/L (CK), 0.12 mol N/L (LN), 0.24 mol N/L (MN) and 0.36 mol N/L (HM) respectively. The photosynthetic characteristics, biomass allocation, C, N and P distribution in response to different N deposition were investigated in one-year-old S. superba seedlings after nine months. The results showed that:(1) The trend of maximum net photosynthetic rate (Pn_max) of S. superba was increased firstly, and then decreased with the increase of nitrogen supply. With the treatment of MN and HN, Pn_max increased by 21.1% (P<0.01) and 16% (P<0.01), respectively. The change of light saturation point (LSP) was similar as the Pn_max. LN and MN caused the increase of LSP by 10.6% (P<0.01) and 13.1% (P<0.01), respectively. But the LSP in the HN was significantly lower than that in the CK (P<0.01). The LCP reduced significantly in LN (P<0.05), and Rd reduced significantly under different N treatments (P<0.01 for LN and MN; P<0.05 for HN).The apparent quantum yield (AQY) were of no significant difference under the different N treatments. (2) N deposition enhanced total biomass, leaf biomass, stem biomass and root biomass of S. superba seedlings significantly. The treatments of MN and HN induced the increase of total biomass by 168.5% (MN, P<0.01) and 130.5% (HN, P<0.05), respectively. Root biomass increased by 145.6% with MN treatments (P<0.01). N treatments caused significant increase of leaf biomass by 247.4% (MN, P<0.01) and 228.5% (HN, P<0.01). Leaf weight ratio increased while root weight ratio and root to shoot ratio reduced with different concentration of N treatments. (3) N concentrations increased, but P concentrations decreased in soil upon N deposition. Under HN, the N concentrations increased by 44.65% (P<0.01), 35.06% (P<0.01) and 24.78% (P<0.05) in roots, stems and leaves respectively. The C concentrations inclined firstly, and then declined with the increase of nitrogen supply in the roots, stems and leaves. Furthermore, C concentrations of different organs increased significantly under MN in comparison with CK (P<0.01 for roots and stems, P<0.05 for leaves).The change of P concentrations in the roots appeared positively to LN and MN, but negatively to HN. However, P concentrations in the stems and leaves appeared negatively to N deposition (P<0.01).To a certain extent, N deposition induced the decrease of C/N ratio and the increase of N/P ratio in the roots, stem and leave of S. superba seedlings.