The invention relates to a gelatinizer including the following components, by weight: 30-350 parts of magnesium- and aluminum-rich silicate (Mg5Si8O20(OH)2(OH2)4.4H2O), 80-150 parts of high-activity aluminum silicate, 5-15 parts of boric acid (H3BO3), 5-15 parts of citric acid (C6H8O7), 2-15 parts of phosphoric acid (H3PO4), 5-10 parts of silicon sol (SiO2.nH2O), 1-3 parts of a siloxane waterproof agent, 800-1200 parts of light calcined magnesium oxide, 300-500 parts of magnesium chloride hexahydrate, 80-120 parts of magnesium sulfate heptahydrate, and 400-600 parts of water. The gelatinizer, on the basis of maintaining the technical indices, such as fireproof performance, waterproof performance and the like, is free of formaldehyde when being used for cementing and adhering various building decorative materials, so that the gelatinizer increases utilization rate of house, provides a green and environment-friendly living environment, and is beneficial to body health of residents.