The invention discloses a novel nanometer flame-retardant composite material. The composite material is characterized by comprises the following substances by weight: 35 to 70 parts of glass fiber reinforced polyethylene terephthalate ester, 15 to 23 parts of rare earth phenyl phosphonate, 10 to 20 parts of aluminum hydroxide, 3 to 8 parts of ethylene acrylate, 1 to 9 parts of high density polyethylene, 5 to 9 parts of diammonium phosphate, 3 to 11 parts of hexabromo water dispersion, 4 to 12 parts of superoxide dismutase, 10 to 18 parts of tetra(3,5-di-tert-butyl-4-hydroxy)pentaerythritol phenylpropionate, 20 to 31 parts of methyl benzoate, 5 to 17 parts of polyvinyl alcohol and 10 to 24 parts of chlorobenzene. The novel nanometer flame-retardant composite material has a wide application scope, reduces the usage amount of a fire retardant, enables cost to be saved, accords with the trend of environmental protection and conservation, is simple and easy to prepare and process, exerts an obvious effect, accords with practical application conditions and is quite possible to be marketed.