Abstract: Rainstorm waterlogging is one of the main consequences of the urban storm flood disaster. Based on the distribution of drainage areas and given rainfall volume, we proposed an urban rainstorm waterlogging calculation model. Two hypotheses for the mechanism and characteristics of urban waterlogging were introduced. According to the spatial feature of waterlogging sources, the urban watershed was divided into several drainage areas that serve as the calculation cells of the calculation model. In order to ensure the efficiency, the internal space of each drainage area was simplified to a regular geometric figure based on the terrain factors, so that the waterlogging of each source and the water spreading between different sources can be simulated using the bulk algorithm and different spreading calculation methods. The illustrative case shows that the calculation model is effective and feasible, which has some application value in waterlogging modeling under the condition of incomplete information.