The invention belongs to the field of inorganic non-metallic materials and relates to a method and device for preparing porous ceramic by a heavy gas-protective direct-foaming technology. The method comprises preparing suspension slurry, carrying out vacuum bubble-removal, removing environment air by heavy gas, carrying out heavy gas-protective stirring foaming, carrying out pouring, carrying out demolding, carrying out drying and carrying out sintering. The foamed ceramic is prepared by heavy gas (such as argon or carbon dioxide)-protective stirring foaming and the water-based ceramic slurry foaming special-purpose device is designed. The method for preparing the foamed ceramic adopts a stirring foaming method adopting heavy gas to extrude air upward, utilizes simple equipment and is convenient for operation. The foamed ceramic slurry undergoes a free radical polymerization reaction for gelation curing, has a fast gelation rate, has uniform blank aperture distribution and is suitable for preparation of a porous ceramic material with apertures of 50-300 microns.