The invention discloses a high-strength aluminum-copper alloy for aerospace structural parts and a preparation method, and belongs to the technical field of aluminum alloys. The aluminum alloy comprises the following components in percentage by weight: 4.5-5.5% of Cu, 0.25-0.60% of Mn, 0.12-0.30% of Ti, 1t of Mg, 0.12-0.30% of Mn and the balance of Al. %, 0.30 wt.%, Si: lt; %, 0.25 wt.%, Fe: lt; %, 0.20 wt.%, 0.20 to 0.60 wt.% of Ag or 0.15 to 0.30 wt.% of Sn, with the balance being Al. The preparation method comprises the steps of burdening, preheating, smelting, molten aluminum treatment, intermediate alloy adding, casting, solid solution quenching and aging treatment. The high-strength aluminum-copper alloy for the aerospace structural component is excellent in obdurability matching effect, and the organization structure of a high-strength aluminum-copper alloy casting obtained after heat treatment is also superior to that of an existing aerospace structural component.