The invention relates to a device for feeding water for a flowerpot. The device comprises an outer pot, wherein an inner pot is arranged in the outer pot, and a capillary water guiding band is arranged between the outer pot and the inner pot. As a preferred scheme, the opening of the inner pot is higher than that of the outer pot. It is preferred that the opening of the inner pot is higher than that of the outer pot about 5 cm to 10 cm. As a preferred scheme, the outer pot and the inner pot are integrally formed. The device for automatically feeding water for the flowerpot is composed of the inner pot and the outer pot, soil is placed in the inner pot and used for cultivating flowers, water is stored in the outer pot, and a proper amount of water can be kept in the soil of the inner pot by the capillary water guiding band between the inner layer and the outer layer through the capillary phenomenon. Due to the structure of the inner pot and the outer pot and the capillary water guiding band, water can be fed in time. Besides, because the water guiding amount is small, it is avoided that water in the inner pot is too much. The device is small in size and can be conveniently placed in a balcony and other places small in space.