Abstract: There are seven acid rain monitoring stations in Anhui province operated by Anhui meteorological bureau. According to the measurements at those seven stations and the field observations of rain chemistry at Mountain Huangshan and Hefei, together with results in previous studies, the trend of precipitation acidity and characteristics of acid precipitation in Anhui province were analyzed. The main conclusions were summarized as follow: (1)During 2006-2013, strong acid precipitation can be observed at all stations, no matter whether in southern or northern Anhui, at urban site or at alpine site. Among the seven stations, precipitations at Hefei and Anqing stations were the most prominent for the highest frequencies of strong acid precipitation, and with the eight-year volume-weight-mean (VWM) pH close to 4.5 (critical value of strong acid precipitation). Based on the eight-year VWM pH, only precipitation at Fuyang station belonged to non-acid type; precipitations at all other stations belonged to acid type. The acidity show evident seasonal variation, severe in winter and light in summer. (2) For all stations, the acid precipitation was the most severe around 2009. Since then, acid precipitation generally showed trend of mitigation. Taking Hefei as an example, the variation trend of acid precipitation from 1992 to 2013 could be divided into three phases: from 1992 to 1999, annual VWM pH showed big yearly variation without evident changing trend; from 2000 to 2008, the precipitation acidity increased with decreasing annual VWM pH and increasing frequency of acid and strong acid precipitation; from 2009 to 2013, the precipitation acidity mitigated slightly. (3) As far as polluted degree is concerned, precipitation at Mountain Huangshan was the cleanest, followed by precipitations at Anqing; precipitations at Tongling and Maanshan were polluted heaviest. (4) As for ions composition, the acidity of present rainwater came from both nitric and sulfuric acids, with the predominant acidic anion. Comparing with compositions of 1980s and 1990s, the concentrations of and increased evidently. Since 2005 or 2006, Anhui and the surrounding provinces kept reducing SO2 emissions, which was the major reason of precipitation acidity mitigation. However, the rapid increase of tropospheric NO2 during the past ten years resulted in the acid type of precipitation changing from sulfuric acid to mixture of nitric and sulfuric acids.