The invention relates to a gas sensing material of cuprous oxide and stannic oxide micro-nano heterogeneous medium array structure and a preparing method thereof, and belongs to the technical field related to gas sensing materials. The structure of the gas sensing material is a film material formed by periodically alternately assembling Cu2O and SnO2 which are parallel in elongated shapes, and the film material is generated on a silicon chip substrate, a Cu2O material is stacked thickly to form a protuberance portion, and a SnO2 material is stacked thinly to form a low ebb portion. The preparing method comprises parallelly placing two copper foil electrodes on a silicon substrate, dripping electrolyte prepared by copper nitrate and stannous chloride between the electrodes, covering a cover glass, refrigerating, solidifying and applying half-sine wave voltage, and enabling Cu2O and SnO2 to precipitate periodically and alternately. The gas sensing material of the heterogeneous medium array structure has gas sensing characteristics, the sensitivity of gas sensing elements is high at a room temperature because the gas sensing material has stable ordered heterogeneous medium structure, the service life is longe, simultaneously energy is saved and the environment is protected.