Abstract: In view of the faults of polypropylene (PP)fiber like insufficient tensile strength and low rigidity, the PP/high-density polyethylene (PE-HD)/graphene composite fibers were prepared by a melt-spinning method, and the effect of graphene on their properties was investigated by polarizing microscope, tensile experiment, scanning electron microscope, differential scanning calorimeter and Fourier-infrared spectrometer. The results indicated that the tensile strength of the composite fibers reached 2.46 GPa at the PE-HD content of 25 phr, which increased by 8 % compared to pure PP fiber. When 0.3 phr of graphene were incorporated, the composite fibers gained an increase in tensile strength by 1.6 % compared to the pristine PP/PE-HD fiber. The thermal stability of the fibers was also improved with the addition of PE-HD and graphene.