The present invention discloses a flame-retardant waterproof thermal-insulation material, which comprises the following raw materials by weight: 15-25 parts of polyvinyl alcohol, 12-25 parts of light ash calcium powder, 8-18 parts of hydroxymethyl cellulose, 3-7 parts of a water repellent, 8-12 parts of negative ion powder for building, 10-16 parts of a mineral soil filler, 8-14 parts of a flame retardant agent, 6-12 parts of reinforcing fiber, 7-15 parts of an inorganic binder, and 35-45 parts of water. According to the present invention, the flame-retardant waterproof thermal-insulation material has advantages of low water absorption, low thermal conductivity, good thermal insulation, good fire resistance, good stability, strong mechanical strength, friction resistance, corrosion resistance and long service life, can lastingly release negative ions and absorb pollutants in air so as to achieve the air purification effect, and further has characteristics of safe and reliable raw material components, no environment pollution, easily available raw material, low cost, simple process, high practical value, and good application prospect.