Underground drainage system with first water storage and last slow infiltration functions

The invention provides an underground drainage system with first water storage and last slow infiltration functions. The underground drainage system comprises a slow infiltration drainage structure with a filtering material, a reinforced top cover, a plurality of water permeation and water inlet openings and a plurality of separation plates. A specific structure is that the underground drainage system is provided with the filtering material which is laid in a slow infiltration drainage structure and is used for preventing suspension particles carried by surface runoff from entering a slow infiltration material; the underground drainage system is provided with the reinforced top cover at the upper part of the slow infiltration drainage structure and the reinforced top cover can be used as a side pavement, a parking lot or a ground activity place; the underground drainage system is provided with the water permeation and water inlet openings which are used for preventing large particles carried by the surface ru