Based on the frequency of acid rain, pH and the contents of NO3- and SO42- in the acid rain of Guangzhou city in recent years, the change of the acid rain type and its ecological implication were studied. The conclusion shows that in the past a few years, the frequency of the acid rain tended to increase, especially after 2001, the trend is becoming more apparently. The acid rain intensity was weak, and the type of acid rain was still belonged to sulphuric acid rain type. But as the contribution to acid rain of SO2 was reducing and the concentration of NOX was increasing rapidly, the type of the acid rain was approaching to nitric acid rain type. Although the type of acid rain is not nitric acid type now, yet this transformation has its profound ecological meaning, especially the influence of nitrogen in the rainfall.
