Soil acidification of tea garden has gradually become into one of the prominent problems in tea production. In order to establish the effective countermeasures against soil acidification of tea garden, by the method of positioning monitoring, soil acidification of tea garden in Jiangsu Province, the trend of soil pH decreasing rate as well as its relationship with acid rain and soil properties were analyzed synchronously in this paper. The results derived from the investigation of 21 typical tea gardens in Jiangsu Province between 2008 and 2010 showed that soil pH values of tea garden were all lower than the optimal pH 5.5 for tea growth, among which, pH values lower than 4.0 accounted for 42.8%. From 2003 to 2010, soil pH decreasing rate of tea garden in Jiangsu province increased firstly but decreased later and the maximum value occurred in 2007. Soil pH decreasing rate of tea garden was affected by the intensity and frequency of acid rain. meanwhile, there were extremely significantly negative correlation between pH decreasing rate and soil organic matter content as well as total exchangeable bases, while significantly negative correlations between pH decreasing rate and soil cation exchange capacity and soil clay content.