The distribution features of acid rain during the recent three years in the Chongqing area are analyzed with the pH data of precipitation measured at 35 weather stations. The results indicate that there are acid rains in most parts of Chongqing, and some of them are very severe. In recent three years, pH values were lower than 4.5 in most areas of Chongqing with the average being 4.07, lower in the western and southeastern areas and higher in the central and northeastern areas. The frequency of precipitation with pH value being lower than 4.5 is very high. The frequency of acid rain in recent three years was 84.05% generally, 27.42% for relatively severe acid rains and 26.23% for severe acid rains in the whole Chongqing. In the downtown area, the frequency of acid rain was 95.42%, 39.54% for acid rains,relatively severe acid rains and 23.86% for severe acid rains. The frequencies of severe acid rains in autumn and winner were higher than those in spring and summer. The seasonal mean pH of precipitation for each season was lower than 4.5. The pH values varied with the season, lower in autumn and winner and higher in spring and summer.