Abstract: Based on acid rain and related contemporaneous meteorological sounding and air pollution data observed in Changchun during 2012-2015,the annual and seasonal characteristics of acid rain and their responses to meteorological conditions and pollutant concentrations were investigated.The results show that Changchun city has experienced a transformation from weak to moderate acid rain area during the studied period.The precipitation pH indicates a fluctuant downward trend and is smaller in autumn and winter than that in spring and summer,while K value shows an opposite trend.More specifically,the acid rain is more likely to occur in precipitation for the small magnitude in Changchun city.In addition,the severe acid rain is closely associated with south or west wind and the pH value in precipitation decreases with the increasing temperature difference and thickness of thermal inversion.Besides,a negative correlation between the pH value of rainfall and the SO₂ and NO₂ concentrations of the previous day is very significant,which suggests the pollution of acid rain in Changchun city is to a large extent attributed to SO₂ and NO₂ concentrations.