Abstract: A liquid extraction device for a vacuum cleaner includes a base equipped with wheels, a container having an opening and a closed bottom end received on the base, a cover sealedly mounted over the opening of the container and a filter assembly fixedly attached to and below the cover. The cover has a connecting port adapted to be connected to the vacuum cleaner. The container has a sucking port adapted to be connected to a working head and a deflector neighboring the sucking port and extending toward the bottom end of the container. A float is mounted on the filter assembly whereby when liquid in the container has reached a predetermined level, the float will be lifted to block the connecting port of the cover.