The invention discloses a floating type sewage flocculation processing device and an energy storage method by adopting the same, and belongs to the technical field of wastewater processing. In the conventional sewage flocculation processing, the used flocculating agent is produced through a chemical method, which consumes much energy, furthermore, the pollution is generated during the process of flocculating agent production, and the conventional flocculating agent producing device cannot store the electric energy. The cathode has a flat plate structure, which comprises three layers: an upper layer, a medium layer, and a lower layer from top to bottom. The anode is a rectangular block and is made of aluminum alloy, iron alloy, or aluminum-iron alloy. The cathode is opposite to the anode. The cathode is arranged above the anode. A floating block is fixed on the lateral wall of the cathode. The data signal output terminal of a water quality sensor is connected to the data signal input terminal of a controller. The control signal output terminal of the controller is connected to the control terminal of a controllable switch, one end of the controllable switch is connected to the anode, and the other end of the controllable switch is connected to the cathode. The provided device can process wastewater and generate electric energy at the same time.