The invention discloses a flame-retardant reinforced high temperature nylon composite material. The composite material is prepared by blending the following raw materials, by weight, 25-65 parts of PPA, 3-15 parts of PA66, 15-50 parts of glass fiber, 15-22 parts of a bromine family flame retardant, 4-10 parts of a metal oxide flame retardant, 0.4-1 part of an antioxidant, 0.1-1 part of a lubricant and 0.1-1 part of a coupling agent. The invention also discloses a preparation method of the composite material. The method comprises the following steps: uniformly mixing the above raw materials except the glass fiber in a mixer, pouring the obtained mixture into a storage hopper under a feeding speed of 16-20hz, adding the mixture to an extruder, carrying out shearing blending, adding the glass fiber, carrying out melt extrusion, and granulating to obtain the composite material, wherein the extrusion speed is 320-400rpm, and the processing temperature is 280-310DEG C. The composite material has the advantages of high temperature resistance, high strength, good fluidity, good processing performance, good flame retardation property, and hydrolysis resistance.