Based on the precipitation data from the regional weather stations over Xi’an and the data of 1∶10000 geography information，population density, house floor space, local average GDP and so on, by means of weighting synthesis method, the regionalization is conducted in the aspects of sensitivity, risk, vulnerability, and capability of disaster prevention and reduction. Simultaneously, a more scientific and reasonably urban waterlogging disaster risk index of regionalization is devised by simulating the waterlogging distributed situation using the Xi’an Severeg Precipitation Waterlogging Disaster Forecast System, which has been put to operational use.