Drainage device of filter

The utility model provides a drainage device of a filter. Comprising a filter, a drain pipe arranged on the filter in a communicating manner, a support frame with the bottom arranged on the drain pipe, and a suspension rope with the top end arranged on the top of the support frame, the plugging piece is arranged at the bottom end of the suspension rope, corresponds to the drainage pipe in position, and is used for tightly abutting against an outlet of the drainage pipe to close the drainage pipe during suction filtration of the filter and separating from the drainage pipe to communicate the drainage pipe during drainage of the filter; the auxiliary device is arranged between the top of the support frame and the top end of the suspension rope and is used for keeping the plugging piece away from an outlet of the drainage pipe when the filter drains water and the plugging piece is separated from the drainage pipe so as to prevent the plugging piece from interfering with drainage of the drainage pipe and keeping