Abstract: The nine observation stations had been established to determied the acidity and some ions in the precipitation over urban area of Hangzhou during 1983.These deteminations show that the frequency of acid rain presence is 81.4%, the variation of pH value is 4.03-8.80 and the average of pH is 4.58.Occured acid rain is mostly in regions of pH 4.3-4.8.The acidity and frequency of precipitation are highest in industrial area of over urban. The concentration of some ions in snow is higher than rain.