Flood drainage device and method

The invention discloses a flood drainage device and a flood drainage method, and relates to the technical field of municipal flood drainage devices.The flood drainage device comprises a well base and a cover body erected on the well base, two water leakage holes are symmetrically formed in the cover body, and two water guide pipes corresponding to the water leakage holes are fixedly arranged at the bottom of the cover body; a sleeve with a closed bottom end is arranged on the water guide pipe in a sealing and sliding mode, and a plurality of siphons distributed in a circumferential array mode are arranged at the bottom end of the sleeve; a plurality of drainage strips which are uniformly distributed are arranged on the cover body, a same mounting frame is fixedly connected between the two sleeves, a plurality of sealing plates matched with the drainage strips are fixedly arranged on the mounting frame, a tension spring is arranged between the mounting frame and the cover body, and the sealing plates block the