The invention discloses a polypropylene composite material with high strength and toughness and a preparation method thereof. The composite material comprises the following components in parts by weight: 28-58.5 parts of polypropylene, 10-40 parts of polycaprolactam, 14 parts of barium sulphate, 7 parts of glass fiber, 9 parts of compatilizer, 1 part of lubricant and 0.5-1 part of antioxidant; and the preparation method is as follow: drying the barium sulphate, the lubricant and the compatilizer, stirring at the temperature of 40-100 DEG C, evenly mixing the processed barium sulphate, polypropylene and polycaprolactam, performing melt blending by a double-screw extruder, introducing the glass fiber in the middle section of a screw, extruding, drawing and pelleting. The polypropylene has higher flexural modulus, tensile strength and impact strength which are endowed from the synergic toughness-strength enhancement effect of the inorganic rigid particle barium sulphate and the organic rigid resin polycaprolactam and the strength enhancement effect of the glass fiber, thus the composite material can be used as a plastic structure part.