The invention provides a cylinder washing
machine and a control method thereof. The cylinder washing
machine comprises an inner cylinder. Washing water is contained inside the inner cylinder when clothes are washed. The inner cylinder is provided with an inner cylinder opening, an inner cylinder bottom opposite to the inner cylinder opening, and an inner cylinder wall which is connected with the inner cylinder bottom in an enclosed mode to form an inner containing cavity. The inner cylinder wall is provided with an inner-
diameter expanding section and an inner-
diameter reducing section. The inner
diameter of the inner-diameter expanding section is gradually increased in the direction from the inner cylinder opening to the inner cylinder bottom, and the inner diameter of the inner-diameterreducing section is gradually decreased in the direction from the inner cylinder opening to the inner cylinder bottom. In the
dewatering process of the cylinder washing
machine disclosed by the invention, a
dewatering device can be started under the effect of
centrifugal force through rotation of the inner cylinder, component force of the
centrifugal force in the cylinder wall direction of the inner-diameter expanding section and the inner-diameter reducing section acts on the washing water inside the inner cylinder, the washing water moves to the largest inner-diameter end along the cylinderwall and then is discharged through the
dewatering device, and the high-efficiency
dehydration property and centrifugal dewatering property of the hole-free inner cylinder are effectively achieved.