The invention discloses a hyperbranched polyamidoamine modified plant fiber reinforced polypropylene micro foaming composite material and a preparation method thereof. The hyperbranched polyamidoaminemodified plant fiber reinforced polypropylene micro foaming composite material consists of 97-98 wt% of polypropylene composite material and 2-3 wt% of chemical foaming agent, wherein the polypropylene composite material consists of polypropylene, hyperbranched polyamidoamine plant fiber, PP-g-GMA, antioxidant, lubricant and other additives. The hyperbranched polyamidoamine modified plant fiber reinforced polypropylene micro foaming composite material has the characteristics of low density, high strength, high rigidity, fine cell pores, uniform distribution, etc., can meet application requirements of automobile parts, adapts to development concepts of energy saving and environmental friendliness, and is in line with the development trend of automotive lightweight, therefore, the materialhas a broad development prospect in the field of automobiles.