The present research aims to provide scientific basis for storm water disaster prevention and storm water drainage planning in urban area. Based on monthly precipitation data from 1892 to 2010 at Shapingba meteorological station in Chongqing, we analyzed the precipitation and the frequencies of different precipitation grading in different statistical periods in the past 119 years through linear trend estimation and analysis of variance (ANOVA). We also discussed the trend of precipitation variation in Chongqing urban area. Results showed that annual precipitation and precipitation in flood seasons increased slightly. Annual precipitation increase mainly concentrated in flood seasons. In addition, in the past three decades, the range of annual variation had an obvious expanding trend, and the frequencies of large precipitation also had been increasing significantly. Particularly in the recent decade, annual precipitation variation in urban area had been more intensive and the frequencies of catastrophic climate in continuous period had been increasing, which exacerbated the pressures on drainage system in flood seasons. 