The invention discloses a high-strength flaming retarding polypropylene modified material and a preparation method thereof. The preparation method comprises the following steps of: (1) drying particles of a pure polypropylene material for two hours at a set temperature; (2) uniformly mixing a set addition amount of calcium sulfate crystal whiskers with the particles of the pure polypropylene material; (3) adding a dispersing agent in the mixture of the calcium sulfate crystal whiskers and the particles of the pure polypropylene material according to a set mass percentage and stirring and mixing uniformly; (4) setting the temperature and screw rotating speed of a twin-screw extruder and adding the mixture finally formed in the step (3) in the twin-screw extruder for mixing and continuous extruding; (5) after a material discharge port starts to discharge materials, adding zinc oxide crystal whiskers into the twin-screw extruder from the side material port of the twin-screw extruder and mixing and extruding; and (6) cutting particles, and drying the particles for two hours at a set temperature so as to finally obtain high-strength flaming retarding polypropylene particles. The invention also discloses a high-strength flaming retarding polypropylene modified material.