The invention discloses a method for preparing sintering-free geopolymer foam ceramics. The method comprises the steps of firstly grinding waste/old ceramics into powder, then, uniformly mixing and stirring 100 parts by weight of ceramic powder, 30-60 parts by weight of alkaline activator and 1-5 parts by weight of foamer, pouring a mixture into a mold, curing for 24 hours in a concrete curing box at the temperature of 60 DEG C, then, demolding, and continuously curing for 28 days, thereby obtaining the sintering-free geopolymer foam ceramics. According to the method disclosed by the invention, a high-temperature (1,300 DEG C) and high-energy-consumption sintering process of the general ceramic foam preparation processes is not required, and complicated processes, such as dipping and the like, are also not required, so that the method is energy-saving, low-carbon and environmental-friendly; the geopolymer foam ceramics are prepared by adopting an alkali activating principle, and the interior of the geopolymer foam ceramics contains a great deal of amorphous three-dimensional reticular structures, so that the material has the characteristics of low heat conductivity, good heat insulating property, good fire resistance, long service life, good ageing resistance and the like; the material is an inorganic material, so that the fatal defects of flammability and combustibility of organic heat insulating materials are overcome.