A method for preparing an aluminum alloy for a vehicle integral die-cast part, characterized in that the aluminum alloy comprises 7-9 wt% of Si, 0.05-0.25 wt% of Mg, Cu < 0.5 wt%, Zn < 0.5 wt%, 0.001-0.20 wt% of B, 0.05-0.2 wt% of Ti, 0.1-0.9 wt% of Mn, 0.05-0.3 wt% of Fe, 0.005-0.5 wt% of Sr, Ce < 0.5 wt%, 0.01-0.1 wt% of Zr, 0.001-0.3 wt% of Mo, a sum of weight percentages of remaining impurities being controlled to be 1.0 wt% or less, and the balance being Al; the method comprises following steps: 11) putting high-purity aluminum element into a heating furnace, heating the high-purity aluminum element to a temperature of 680°C, and maintaining the temperature for 15 min after melting completely; 12) raising the temperature to 760°C, and adding Si, Zn and Cu elements; 13) lowering the temperature to 730°C, and adding Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce amorphous intermediate alloys; wherein the amorphous intermediate alloys are obtained by a way of following method: placing Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce intermediate alloys as target materials in a closed chamber, evacuating the chamber to a vacuum and introducing argon gas of 100-150 kPa, irradiating four target materials respectively with a pulsed laser beam, and finally collecting mixed amorphous powders of Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce with set compositional ratio; wherein a vacuum degree of the chamber is 10 -5 Pa, and a laser energy density of the pulsed laser beam is more than 100 kW/cm 2; 14) lowering the temperature to 720°C, and adding pure Mg metal material; and 15) performing casting to obtain an aluminum alloy ingot after all raw materials are melted. 11) putting high-purity aluminum element into a heating furnace, heating the high-purity aluminum element to a temperature of 680°C, and maintaining the temperature for 15 min after melting completely; 12) raising the temperature to 760°C, and adding Si, Zn and Cu elements; 13) lowering the temperature to 730°C, and adding Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce amorphous intermediate alloys; wherein the amorphous intermediate alloys are obtained by a way of following method: placing Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce intermediate alloys as target materials in a closed chamber, evacuating the chamber to a vacuum and introducing argon gas of 100-150 kPa, irradiating four target materials respectively with a pulsed laser beam, and finally collecting mixed amorphous powders of Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce with set compositional ratio; wherein a vacuum degree of the chamber is 10 -5 Pa, and a laser energy density of the pulsed laser beam is more than 100 kW/cm 2; placing Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce intermediate alloys as target materials in a closed chamber, evacuating the chamber to a vacuum and introducing argon gas of 100-150 kPa, irradiating four target materials respectively with a pulsed laser beam, and finally collecting mixed amorphous powders of Al-Zr, Al-Mn, Al-Mo and Al-Ti-B-Ce with set compositional ratio; wherein a vacuum degree of the chamber is 10 -5 Pa, and a laser energy density of the pulsed laser beam is more than 100 kW/cm 2; 14) lowering the temperature to 720°C, and adding pure Mg metal material; and 15) performing casting to obtain an aluminum alloy ingot after all raw materials are melted.