The invention relates to a polypropylene film reinforced by modified nano barium sulfate and a preparation method of the polypropylene film and belongs to the technical field of functional packaging materials. The polypropylene film is prepared by using the modified nano barium sulfate as the toughening agent and organic montmorillonite and maleic anhydride grafted polyethylene as the compatibilizer, adding certain reinforcing agent and using PP as base material through blowing. The reinforced composite polypropylene film prepared by the method is good in heat resistance, high in barrier property, high in tensile property, high in breaking elongation rate and good in anti-aging performance, has certain flame retardance, and is widely applicable to fields such as daily necessities and household appliances.