The EANET measurements of precipitation chemistry were analyzed to assess temporal variations of the pH and major ion concentrations on a regional basis. The concentration, C, was transformed into pC= -log© to be coherent with pH. Three parameters were chosen to represent the annual chemistry of the region: their annual median (MED), arithmetic mean (MEAN), and VWM which was the negative logarithm of the volume-weighted mean of the raw measurements of the year. For the analysis, the measurements were grouped into three because chemistry of China was sometimes significantly different from those of the other countries: China-ON (the total sites), China-OFF, and China-ONLY. For pH, in the case of China-ON,  the MED and MEAN  decreased until 2005 whereas the VWM almost remained, and after this year all three pHs continued to increase with fluctuation.  Similar temporal variations were noted in China-OFF.  In China-ONLY, the mean and the VWM pH decreased until 2010-2011, and then began to increase steeply.  On average, the pH first decreased for the first five years and then changed to increase afterwards. In the p(nss-SO₄^2-) case, the temporal patterns were different from those of pH. The MED and MEAN in China-ON continued to increase throughout the period whereas the VWM increased steeply until 2009, and then grew slowly. In China-OFF, the MED and MEAN showed general increases over the period whereas the VWM began to decrease slowly in 2009. In China-ONLY, the MEAN and VWM commonly increased with fluctuations.  The acid-base chemistry was discussed to understand the pH variations.