The effects of simulated acid deposition on chemical properties of surface runoff were studied in a monsoon evergreen broad-leaved forest in Dinghushan Nature Reserve. Four gradients of simulated acid rain treatments with three replications were designed: control (natural lake water, pH 4.5±0.3), pH 4.0, pH 3.5 and pH 3.0. The surface runoff pH, nitric acid (NO₃^-), sulfuric acid (SO₄^2-), bicarbonate (HCO₃^-), base cations (K⁺, Na⁺, Ca²⁺, Mg²⁺) and dissolved organic carbon (DOC) were detected from October 2011 to March 2012. The result showed that the surface runoff pH was not significantly different among treatments, which exhibited "U" patterns with increasing acid intensity. This suggested the pH was unlikely to decline in a short time. The NO₃^- and SO₄^2- concentrations increased with acid increment, while HCO₃^- exhibited the same pattern as the surface runoff pH. According to the correlation between acid ions concentrations and the surface runoff pH, we found that SO₄^2- and HCO₃^- promoted the ability of anti-acidification, while NO₃^- was adverse. Base cations responded differently to simulated acid treatments. Ca²⁺ and Na⁺ were very sensitive to acid deposition, and their concentrations at pH 3.0 treatment were significantly higher than at other acid treatments. Mg²⁺ concentration increased with the simulated acid intensity, however, there were not significant differences among different acid treatments. K⁺, however, was not sensitive to acid treatment. These results indicated that pH 3.0 treatment led to the loss of Na⁺, Ca²⁺ and Mg²⁺ from the soil. In addition, acid treatments tended to cause dissolved organic carbon (DOC) loss, increasing the risk of organic contamination in the surface runoff.