To explore the practical application modes of underground reservoir system engineering in sponge city construction, the concepts, classifications and engineering practice on underground reservoirs at home and abroad were reviewed. The connotation and request of a sponge city, the advantages of underground reservoirs in sponge city construction and the basic principles of regulation, purification and water cycle path were presented. The feasibility of underground reservoir system in the application of sponge city construction was also demonstrated. Based on the key principles in sponge city construction, such as infiltration, detention, storage, purifying, and drainage, an overall structure of an underground reservoir system engineering was designed. The overall structure consists of eight systems, including surface water impoundment, land rainwater collection, recharge, groundwater storage, water intaking, water discharge, wastewater discharge and treatment, and central monitoring projects.