Abstract: Taking daily rainfall data from 1961-2006 in Hangzhou-Jiaxing-Huzhou area and using statistical analysis, linear regression, R/S method, concentration degree and concentration period,this paper analyzes the effects of urbanization on the long term precipitation. The results show that with the development of urbanization, the increasing trend of annual precipitation, flood season precipitation, heavy rain days and storm rainfall days in urban areas is more than the suburban areas, the difference of urban and suburban areas is increasing and the urban precipitation increasing effect is evident. The precipitation concentration degree is on the decline in urban and suburban areas, and the rate of decrease in suburban areas is slightly more than urban areas. However, the winter precipitation shows the regional characteristics, the light rain days and moderate rain days are uncertain,reflecting the complexity of the impacts of urbanization on precipitation.