The properties of p olypropylene (PP) plastics under the action of light and heat will be greatly reduced. The flame retardancy of PP is relatively poor, thus limiting its application fields. In order to solve the above problems, PP/ANF composites were prepared by using poly (p-benzamide) aramid fiber (ANF) as filler. The excellent high temperature resistance and thermal aging resistance of ANF can effectively improve the flame retardancy and aging resistance of the composites. The results show that the PP/ANF-3 sample with an ANF addition of 6% exhibits the best thermal stability. In terms of mechanical properties, the tensile strength and bending strength of PP/ANF-3 reached 37.8 MPa and 49.3 MPa respectively, which reached the maximum value in all the samples. In terms of flame retardancy, the limited oxygen index (LOI) of PP/ANF-3 is 29.1%, and it shows excellent combustion performance and has good combustion safety. Anti-aging experiments show that PP/ANF-3 exhibits the best whiteness retention rate and the lowest mass loss rate, and the LOI only decreased by 1.6% after aging, which has excellent anti-aging properties. The study indicates that ANF can be effectively used as PP filler to improve its anti-aging properties and flame retardancy.