Based on the self-recorded rainfall data by minute in Xi'an from 1961to 2011,a total of 51 years,a statistics was conducted by segment on the annual rainfall and the number of rainy days,the annual heavy rainfall and the number of rain days,the annual storm rainfall and the number of storm days and the designed rainfall intensity with 5aas the interval,and an analysis was conducted on the rainfall patterns in Xi'an with Mann-Kendall mutation analysis and linear trend methods.The results showed that the annual rainfall and the number of rainy days were both reduced,and a greater magnitude of decrease was showed in the number of days of rainfall since 2005,while the number of heavy rain and storms days and the rainfall increased,the rainfall increased much greater,indicating that the concentration of rainfall and heavy rain and storms increased,and the heavy rain and storms occurred in higher frequency after 2005.The return period of the same intensity of rainfall was smaller after 2005,the rain intensity in the same return period was greater after 2005,each period intensity of rainfall in the segment from 2005to 2009in the return period of 1~5areached the maximum,and the reasons for the change of rainfall patterns in Xi'an City was analyzed in combination with climate change and urbanization.The calculation of rainfall intensity formula based on historical data of rainfall under the conditions of climate change and rainfall patterns changing,the problems existed in the designing of rainwater drainage network,and the relationship between the system and urban waterlogging were also discussed.