Polypropylene composition and polypropylene flat filament and preparation method thereof

The invention provides a polypropylene composition, a polypropylene flat filament prepared from the polypropylene composition, a preparation method of the polypropylene flat filament, and the polypropylene flat filament prepared by the method. The polypropylene composition comprises polypropylene and a nucleating agent; the molecular weight distribution index of the polypropylene is 2.5-5.5, and polymer tail index PIHT in molecular weight distribution width is greater than 1.9. The mechanical strength of the polypropylene flat filament is high.