Drainage device and washing device formed by same

The drainage device comprises a first drainage pump and a second drainage pump which are installed at the drainage end of a washing device, a water inlet and a water outlet are formed in a pump shell of the first drainage pump, a water pumping cavity is formed in a water path where the water inlet and the water outlet are communicated, and an impeller is arranged in the water pumping cavity; the pump shell is provided with a driving device for driving the impeller to pump water in the water pumping cavity to the water outlet, the water draining end of the second water draining pump is connected with a water draining slim pipe, and the water draining end of the filtering mechanism is connected with the second water draining pump; and the second drainage pump pumps residual water in the water pumping cavity to the drainage slim pipe after passing through the filtering mechanism. The problem of completely discharging residual sewage can be solved, impurities in the residual sewage can be filtered, the phenomenon