By analyzing the relationship between underground space and urban flood disaster environment, the key factors affecting underground space flood disasters are determined to be terrain elevation value, rainfall intensity, surface impermeability rate, and pump station scale, and single factor, double factor, and three factor impact analysis are conducted. The results indicate that: Terrain elevation and rainfall are the decisive factors affecting urban underground space under flood disasters. The terrain elevation or fortification elevation of the site should be higher than the terrain elevation under the flood defense capability of the area; The depth of surface water accumulation and the frequency of rainfall exhibit a power function distribution. Beyond the critical rainfall frequency, the depth of water accumulation increases nonlinearly exponentially; There is a logarithmic relationship between the depth of accumulated water and the surface impermeability rate. The smaller the permeability rate, the larger the impact range of accumulated water. By optimizing the selection of underground space entrances and exits, increasing defense elevations, renovating drainage systems, and enhancing regional flood control capabilities, the risk of waterlogging can be reduced; Reducing urban surface impermeability through resilient city construction is an important way to cope with the impact of rainfall, especially to reduce the speed of water accumulation in the early stages of rainfall; Measures should be taken to deal with the collapse and inundation of underground spaces near flood control embankments.