The observed data of acid rain and pollution source are analyzed, and the analysis shows that the frequency of Nanning acid rain is high and the pH value is low.The computational results of the Lagrange plume model indicate that the Nanning acid rain is mainly affected by external pollution sources.The synoptic diagnoses for pollution sources suggest that the Nanning acid rain is mainly affected by the NE pollution source,especially in winter and spring,and it is influenced also by wind frequency and inversion.Based on above analyses,we conclude several types of circulations affecting acid rain,among those,the upper trough-cold front type is the major one.