The invention discloses an anti-yellowing flame-retardant weather-resistant polypropylene composition and a preparation method thereof. The anti-yellowing flame-retardant weather-resistant polypropylene composition consists of the following components in percentage by weight: 58.5-82.7 percent of polypropylene, 3-8 percent of halogen-series flame retardant, 1.5-4 percent of flame-retardant synergist, 10-20 percent of mineral intensifier, 2-5 percent of light screener, 0.1-1 percent of light absorbing agent, 0.1-1 percent of hindered anime light stabilizer, 0.1-0.5 percent of main antioxidant, 0.1-0.5 percent of auxiliary antioxidant, 0.3-1 percent of processing aid and 0.1-0.5 percent of coloring agent. The flame retardant rating of the polypropylene composition provided by the invention is up to UL94V-2, high mechanical performance can be kept under long-term outdoor or ultraviolet ray irradiation, the yellowing degree is low, and the weather resistance of the material is greatly improved. The anti-yellowing flame-retardant weather-resistant polypropylene composition is mainly applied to home appliance components, large-sized outdoor stadium plastic seats, automobile parts and the like which are influenced by ultraviolet rays.