Abstract: A circularly cleaning swab structure mainly composed of a grip stem, a casing and an annular water-absorbing member. The casing is connected at a lower end of the grip stem and has an upper cover secured on an upper opening of the casing by fasteners to define an interior close water-containing room. The water-absorbing member is disposed around outer periphery of the casing and formed with inner engaging teeth for engaging with corresponding teeth of a rotary wheel rotatably disposed on an outer lateral side of the casing. A top portion of the water-absorbing member is inserted within a clearance defined between the casing and the upper cover while a bottom portion of the water-absorbing member is located under a bottom of the casing for contacting the ground.