The invention discloses a high-temperature humidity-resistant glass fiber reinforced nylon composite material , wherein the preparation raw material comprises the following components in mass percentage: 30% to 40% of nylon 66, 15% to 25% of polyphthalamide resin, 10% to 20% of long glass fiber, 5% to 10% of polycarbonate, 5% to 15% of an inorganic filler, 3% to 7% of modified sepiolite, 1% to 5% of a compatibilizer, 0. 5% to 1.5% of a lubricant, 0.5% to 2.5% of an impact modifier, and 0.5% to 3.5% of a flame retardant. The invention also discloses a preparation method of the high-temperature-resistant moisture-resistant glass fiber reinforced nylon composite material. The glass fiber reinforced nylon composite material has excellent mechanical properties, impact resistance and flame retardancy, and can maintain high mechanical strength under high temperature and high humidity environment, ensuring dimensional stability and good processability. Surface roughness and warpage are not easy to appear, high use demand is met, and wide application in the field of engineering plastics can be realized.