本文利用2000年以来中国气象局的酸雨观测站网的观测资料，分析了近年来我国酸雨形势出现的一些新的变化，其中京津地区近年来酸雨程度与2000年前相比明显地逐年加重趋势最值得关注。本文着重分析了京津地区的酸雨程度的长期变化趋势，指出：为了迎接奥运会近年来北京等地加大了空气污染的治理力度，大气颗粒物总浓度的逐年下降，一次颗粒物如扬尘、工业粉尘对降水酸性的中和能力减弱，二次颗粒物如硫酸盐、硝酸盐等浓度和比例的升高，可能是近年来京津地区降水酸性明显增加的重要原因；这种情况提示我们，区域降水酸性对近年来采取的相关环境治理措施具有敏感的响应。

This paper presents the trend analysis of precipitation acidity over China based on the records of pH value of precipitation obtained from Acid Rain Monitoring Network operated by China Meteorological Administration, with an emphasis on Beijing-Tianjin region. The analysis shows that the area of precipitation acidification, with low pH value and high frequency of acid rain, extends significantly over China in recent years, and that especially the acidity of precipitation in Beijing-Tianjin area has increased significantly since 2000. This trend of increasing acidity of the precipitation within Beijing-Tianjin region corresponds to the decline of the concentrations of airborne particles in Beijing and Tianjin, as a result of the pollutant/particle abatement effort toward 2008 Olympic game in Beijing, suggesting a possible linkage between the trend of precipitation acidity and the particle control measure. This linkage implied the sensitive response of the precipitation acidity on the control of particulate pollutants in a regional scale.