The current study takes the hilly south Anhui province as the study area, which is located in the subtropical China and far from urban and industrial activities. The rainwater samples were collected from April to November in 2007 and were determined for pH, major cations and anions, to estimate acidity characteristics and the sum of hydrogen ion and other cation and anion input during the studied period. The results showed that the frequency of acid rain was over 92%, with an average pH of 4.61. The average concentrations of SO4(2-) and Ca2+ were 39.69 microeq/L and 68.82 microeq/L respectively, which were the most abundant cation and anion among the determined elements. The atmospheric pollution was characterized as SO2 and NOx with an average of SO4(2-)/NO3(-) 1.23 in the rainwater. The variation of the major chemical component in the rainwater with time implied that the atmospheric NOx mainly originated from the local agricultural activities, while SO2 was mainly affected by non-local source and the base cation was mainly affected by dust transportation during spring season. The total input of base cation and H+ was 1,289 eq/hm2 and 360 eq/hm2 respectively, while that of SO4(2-) and NO3(-) was 926 eq/hm2 from April to November in 2007. The input of acid deposition may have a detrimental effect on the local ecosystem.