Drought is one of the most important but least understood issues in global environmental changes. Decrease in soil moisture is an indicator of drought. Here, we analyze summer (June-August) soil moisture measurement data across 50 sites in China in order to investigate the linkage between climate change and drought. At the country scale, a significant decrease in summer soil moisture in the top 50 cm was observed during 1981-2002, resulting mainly from the decline in soil moisture in North China. Statistical analyses suggest that changes in precipitation frequency have significant consequences for soil moisture dynamics, but our ability to use precipitation frequency changes to explain the variation of soil moisture depends on the discriminating criteria of precipitation events. Among five criteria (0, 5, 10, 15, and 20 mm day-1), the maximum coefficient of correlation between summer soil moisture in the top 50 cm and precipitation frequency occurs when considering the number of days on which the daily precipitation amount is larger than 10 mm (PF10). Spatially, the correlation between soil moisture in the top 50 cm and PF10 is weak for very dry and very wet soils and is much stronger for intermediate values.