In nitrogen (N) saturated forest ecosystems, N deposition has been shown to increase NO-3 loss and soil acidity. This reduces soil quality and further influences the sustainable development of the forest. However, the effects of N deposition on forest ecosystems in the red soil region of southern China are not well understood, especially the response of soil leaching solution chemistry to N deposition. In this study, a soil column experiment was conducted to investigate the effects of N deposition on soil leaching solution chemistry for eight months at 20℃. The soil column (10 cm diameter and 60 cm high) was filled with soil collected from a broad_leaved forest at the Red Soil Ecological Experiment Station, Jiangxi Province. The simulated N deposition rates were 0 (control), 7.8, 26 and 52 mg N month-1 col-1. The concentrations of NO^-₃, NH⁺₄, SO^2-₄, H⁺, Ca²⁺, Mg²⁺, K⁺ and Na⁺ in the leachate were measured and basic soil physical and chemical properties were also determined. Results showed that NO-3, H+, exchangeable base cations (Ca²⁺, Mg²⁺, K⁺ and Na⁺), and EC in the leachate increased as simulated N deposition rates increased, but no NH+4 was detected in the leachate of any treatment. Net mineralized soil N increased from 189.6 mgN•col-1 in the control treatment to 554.2 mgN•col-1 in the 52 mgN•month-1•col-1 treatment. N input significantly accelerated the mineralization of soil organic N, and a positive linear relationship existed between the apparent mineralization rate of soil organic N and N input (R2=0.997**). The percentages of total exchangeable base cations leached from the soil to total exchangeable base cations increased from 13.6% in the control treatment to 18.4, 27.7% and 48.1% in the 7.8, 26 and 52mgN•month^-1•col^-1 treatments respectively. Exchangeable base cations responded differently to N deposition. Ca²⁺ and Mg²⁺ leaching losses increased as N deposition increased, but N deposition had no effect on the leaching of K+ and Na+. The percentage of exchangeable Ca²⁺ leached from the columns increased from 22.6% in the control treatment to 31.4, 46.7% and 82.5% in the 7.8, 26 and 52 mgN•month^-1 col^-1 treatments. Similarly the percentage of exchangeable Mg2+ leached from the columns increased from 5.0% in the control treatment to 16.9% in the 52 mgN•month^-1•col^-1 treatment. In contrast, the percentage of exchangeable Na+ leached from the four treatments was 16.0, 10.7, 17.6％ and 26.3% in the 0, 7.8, 26 mgN•month^-1•col^-1 and 52 mgN•month^-1 col^-1 treatments respectively. No exchangeable K+ was observed in the leachate of any treatment. N deposition resulted in a significant decrease (p<0.05) in the amount of sulfate leached from the columns compared to the control. The pH of the surface soil also decreased significantly as N deposition increased. The results from this study indicated that increased N deposition rates will increase soil nutrient losses and soil acidity under broadleaf forests in the red soil region of southern China.