The invention discloses a small device for extracting water from air based on adsorption and semiconductor refrigerating and a method of the small device. The device for extracting water from air comprises an air inlet, an air-inlet fan, electric heating wires, an adsorption bed, an inner shell, an inner shell air outlet, a condensing static-pressure cabin, condensing sheets, a semiconductor refrigerating sheet, heat-insulating cotton, a cooling fan, cooling fins, outer shell air outlets, an outer shell, a reservoir, a water outlet and a base. In an adsorption stage, the air, which is dehumidified by virtue of the adsorption bed, is discharged from the air outlets; and in a desorption water extracting stage, the air, which is heated by virtue of the heating wires, passes through the adsorption bed, and meanwhile the semiconductor refrigerating device begins to work, so that high-humidity air becomes cold and condensed to generate water beads and the water beads flow into the reservoir along the wall surface of the semiconductor refrigerating device. The small device for extracting water from the air provided by the invention has the advantages of being small in volume, simple in structure, compact in parts, capable of extracting water under the circumstance that humidity is quite low and the like.