The invention discloses an aluminum alloy composition and a preparation process thereof, and relates to the technical field of profiles. The preparation process comprises the following steps: 1) putting aluminum into a smelting furnace for smelting, and when the smelting temperature inside the smelting furnace is 680+10 DEG C, adding magnesium oxide and stannic oxide for further smelting; 2) when the smelting temperature is 1600+10 DEG C, adding copper oxide, zinc oxide and silicon carbide, when the temperature is 750+10 DEG C, stopping heating, and preserving heat for 1 hour; 3) analyzing the smelted material by adopting spectral analysis, performing refining treatment at 740+10 DEG C after the material is qualified in the analysis, and further adjusting the smelting if the material is not qualified in the analysis; and 4) standing for 10-20 minutes after the refining is accomplished, putting the material into a heat preservation electric furnace of 720+10 DEG C for heat preservation, and finally casting to form blanks. Due to addition of the silicon carbide component, the problem of leakage caused by directional gap increase as a gear pump shaft sleeve is excessively abraded is effectively solved, and the service life and the output power of a gear pump are prolonged and improved, that is, the service life is 1-3 times longer than that of a conventional pump.