In order to study the effect of a novel bioretention swale with impermeable membrane covered up to pebble layer, physical model test and numerical analysis were used to investigate the infiltration mechanism of bioretention swale subject to different rain event. The results show that bioretention swale with such design feature has excellent rainwater collecting effect and rainwater can infiltrate into the surrounding soil simultaneously. It is concluded that bioretention swale with such design feature to be an ideal component that meets the requirements of sponge city construction and can provide a certain design reference in the sponge city.