The invention provides a nano aluminum oxide and glass fiber composite reinforced nylon material and a preparation method thereof. The obtained material is prepared from raw materials in parts by weight as follows: 45-55 parts of nylon 6 and/or nylon 66, 25-35 parts of chopped glass fiber, 5-15 parts of nano aluminum oxide, 0.1-0.5 parts of a KH550 silane coupling agent, 0.5-0.7 parts of a 140 silane coupling agent, 4-8 parts of a lubricant and 3-5 parts of an antioxidant. The preparation method of the material comprises the steps as follows: A, performing surface modification on the nano aluminum oxide by the KH550 silane coupling agent; B, mixing the nylon 6 and/or nylon 66 and a product in step A, and performing extrusion and granulation; C, performing surface modification on the chopped glass fiber by the 140 silane coupling agent; D, mixing products in steps B and C, the lubricant and the antioxidant, and performing extrusion and granulation to obtain the material. By means of thetechnical scheme, a multi-scale composite reinforced structure can be formed, interface compatibility and strength of nylon resin and glass fiber are enhanced, and the durability of the material is improved.