The invention discloses a light-weight, environmentally-friendly, stable, weather-resistant, flame-retardant and heat-insulating material and a preparation method thereof, the light-weight, environmentally-friendly, stable, weather-resistant, flame-retardant and heat-insulating material comprises the following raw materials by weight: 25 to 35 parts of polyether polyol, 3 to 5 parts of an acid salt auxiliary agent, 15 to 25 parts of mixed resin, 4-6 parts of polyvinyl alcohol, 6-8 parts of a smoke-proof fireproof additive, 10-12 parts of a heat preservation aid, 4-6 parts of a bactericidal additive, 8-10 parts of talcum powder, 6-8 parts of shell powder, 3 to 5 parts of silica sol, 4 to 6 parts of white carbon black, 6 to 8 parts of a coupling agent, and 5 to 9 parts of a processing aid. The light-weight, environmentally-friendly, stable, weather-resistant, flame-retardant and heat-insulating material has the advantages of light weight, low thermal conductivity, good heat preservationeffect, good toughness, good flame retarding effect, stable size, creep resistance, fatigue resistance, long service life and excellent comprehensive performance; and the preparation method has the advantages of easy-to-get raw materials, simple process, high practical value and good application prospects.