Abstract: A top cover, a sealing ring and a filter for an outlet of a washbasin are provided, wherein the filter includes a top cover including a cover body and an inner cover arranged below the cover body, a filter cylinder provided with a number of drainage holes at a cylinder body of the filter cylinder, and a sealing ring including a supporting part and a plugging part arranged at an outer edge of the supporting part; the cover body is configured to be located at a level above an opening surface of a drainer of the washbasin when in use to enable water flow being able to discharge through interspace between the top cover and the opening surface of the drainer, and the plugging part is configured to provide sealing contact with an inner wall of the drainer enabling to deposit sundries at the supporting part.