The invention discloses flame-retardant canvas. High-strength polyester canvas is taken as a base fabric, wherein at least one side of the base fabric is coated with a flame-retardant layer, and the flame-retardant layer is prepared from the following raw materials in parts by weight: 10-12 parts of high-density polyethylene, 5-8 parts of urea-formaldehyde resin, 1-3 parts of ethylenebis(oxyethylenenitrilo)tetraacetic acid, 1-5 parts of 2-hydroxy-3-methyl-2-cyclopenten-1-one, 1-4 parts of N-(2,6-dioxo-3-piperidyl)phthalimide, 2-8 parts of ammonium polyphosphate, 3-6 parts of butadiene, 4-7 parts of anilino-methyl-triethoxysilane, 2-7 parts of octyl phosphate and 2-4 parts of arsenic trioxide. By compounding of raw materials, the final product has excellent flame retardancy and breaking strength, all layers of the prepared canvas are firmly combined, and accordingly, connection of all the layers of the whole product is firmer.