The invention provides flame-retardant wallpaper which comprises a main body layer, a flame-retardant layer and a thin film layer, wherein the flame-retardant layer is a flame retardant applied onto one side of the main body layer; the other side of the main body layer is stuck with the thin film layer through a silane coupling agent; the thin film layer is a polyvinyl acetal film; and raw materials of the main body layer comprise the following components in parts by weight: 30 to 50 parts of pulp, 1 to 5 parts of nano silver particles, 2 to 10 parts of glass fiber, 20 to 40 parts of modifiedfiber and 1 to 5 parts of a flame retardant. The flame-retardant wallpaper provided by the invention can effectively absorb harmful gases such as formaldehyde, benzene, ammonia and the like, and has bactericidal ability; and the multifunctional wallpaper is relatively good in strength, easily torn off from a wall without cracking and good in flame retardant efficiency. A preparation method is simple to operate and low in cost.