The invention relates to an intumescent flame retardant (IFR) which is compounded by adopting ethylene glycol modified melamine formaldehyde resin as a charring agent, adopting ammonium polyphosphateas a dehydrant, adopting melamine polyphosphate as a foaming agent having a dehydration function, and adopting inorganic nanomaterial-hydrotalcite as a synergist. The IFR includes, by mass, 65-75% ofammonium polyphosphate, 15-20% of ethylene glycol modified melamine formaldehyde resin, 5-10% of melamine polyphosphate and 3-6% of hydrotalcite. The IFR is advantageous in that the IFR has good flameretardant and smoke suppression functions for polypropylene; the IFR is substantially free of chlorine so that the IFR is safer and more environmentally friendly; flame retardant polypropylene prepared by utilizing the IFR is good in color, thus benefiting color adjustment; and raw materials are cheap so that the IFR is low in cost.