Piperazine pyrophosphate (PPAP) was compounded with a variety of flame retardants to prepare intumescent flame retardant (IFR), and finally blended with polypropylene (PP) to prepare PP flame retardant composites. These composites were characterized by vertical combustion, limiting oxygen index (LOI), cone calorimetry, thermogravimetric analysis and mechanical properties. The results show that compared with PP samples, the LOI of these composites increases from 17.6% to more than 26%, the carbon residue rate increases from 0.09% to more than 1.98%, and the thermal decomposition T _1% and T _5% increase by 11.4 ℃ and 41.2 ℃, respectively, indicating that the addition of flame retardant enhanced the flame retardant. At the same time, the peak heat release rate, average heat release, total heat release and total smoke production of these composites are greatly reduced, and the flame retardancy and smoke suppression properties are significantly improved, while the mechanical properties are reduced. The flame retardant effect of PPAP and melamine pyrophosphate (DMPY) is the best, in which the LOI is 29.2%, the carbon residue rate is 2.65%, the thermal decomposition T _1% and T _5% are 286.6 °C and 372.7 °C, respectively, and the mechanical properties are the least affected.