The invention discloses a flame-retardant plastic masterbatch, which is prepared from the following raw materials in parts by weight: 20 to 40 parts of matrix resin, 10 to 20 parts of talcum powder, 5 to 10 parts of chlorinated paraffin, 1 to 3 parts of triphenyl phosphite, 40 to 60 parts of pigment, 1 to 2 parts of aluminum hydroxide, 0.02 to 0.2 part of ultraviolet light absorber, and 0.1 to 1 part of antioxidant synergist. The flame-retardant plastic masterbatch provided by the invention has the advantages of simple and stable construction process, excellent mechanical property, flame retardancy and antibacterial property, aging resistance, high temperature resistance and long service life.