Chinese subtropical forest zones have been damaged by long term acid rains. The acid rain usually increases the decomposition rates of soil organic carbon and impacts the release of soil carbon by accelerating the soil acidification. Consequently, an uncertainty of the variation of soil carbon is leaded by the effect. Meanwhile, the effluxes of carbon dioxide CO2 released from soil into the air contribute to a potential climate change. In order to figure out the effect of acid rain on the release of soil carbon, an acid rain menace control experiment was carried out on a compound system of Cunninghamia lanceolata seedling\|soil. The system is sensitive to the acid rain stress in Zhejiang Province and is located in the middle Chinese subtropical areas, which is suffered from the severe acid rain pollution in a long term. The Cunninghamia lanceolata seedling\|soils constructed in plots were divided into three groups, which represented the severe acid rain treatment ST (pH 2.5), the moderate acid rain treatment MT (pH 4.0) and the check experiment CK (pH 5.6). Then the samples were sprayed by artificial acid rains with different pH values in a green house for 2 years. The artificial acid rain was consisted of H2SO4 (98%) and HNO3 (75%) at the volume ratio of 8:1, and was diluted by pure water into spay solutions, of which pH values were 2.5, 4.0 and 5.6 respectively. The trend of soil acidification and the variation of soil respiration in the seedling\|soil system were experimentally analyzed with a response model of soil carbon release developed to simulated acid rain stress. The results showed that (1) the pH\|value of soil treated with CK decreased, but the soil\|buffer system had not been strongly changed. The mass of hydrogen ion H+ rushing into soil due to a severe acid rain (pH 2.5) made the pH\|value decrease to 3.71. Meanwhile the residual of Ca2+ and Mg2+ decreased sharply. After which the soil\|buffer system changed into aluminum buffer system and the soil was apparently acidified. Moderate acid rain (pH 4.0) did not significantly acidify soil, although the pH\|values of soil and the residual of Mg2+ in soil slightly dropped. On the other hand, the residual of Ca2+ remained 40.15-42.76 μg?g-1 (oven\|dried soil). (2) The mean annual effluxes of soil carbon of control group did not strongly vary, which were 1.41 μmol?m-2?s-1 in 2007 and 1.42 μmol?m-2?s-1 in 2008. The acid rain inhibited the soil respiration of Cunninghamia lanceolata seedling\|soil mainly in the first 2 years. Compared to CK, the inter\|annual effluxes of soil respiration of the conifer seedling\|soil sprayed by a severe acid rain (pH 2.5) dropped by 14% and 28% respectively in the two years. Even though the moderate acid rain (pH 4.0) could not make a severe soil acidification, it enhanced the release of soil carbon by 8% in 2007 and reduced the effluxes of soil respiration by 15% in 2008. Moreover, the effect of acid rain on the release of soil carbon became more significant with the prolongation of simulated acid rain.