The increase of urban impervious surface, especially the effective impervious surface, has an impact on all aspects of the urban hydrological cycle. Aiming at the problem of urban effective impervious surface and its identification, the hydrological effect of impervious surface is analyzed, and the advantages and disadvantages of using total impervious area and effective impervious area to measure urban imperviousness are analyzed from the perspective of hydrology. The advantages and disadvantages of effective impervious surface identification methods commonly used at home and abroad, such as field survey and measurement method, remote sensing and image data analysis method, land use type determination method, empirical formula method and rainfall-runoff relationship method, are systematically combed. It is pointed out that in the future, it is necessary to deeply analyze the relationship between different types of impervious surfaces of cities and their impact on urban rainfall and flood process, so as to improve the accuracy of urban stormwater simulation and provide technical support for urban flood prevention and control and sponge city construction.