The invention discloses an aluminum alloy high-voltage cable aluminum copper composite terminal. The aluminum alloy high-voltage cable aluminum copper composite terminal comprises a copper alloy substrate and connecting grooves formed in the two ends of the copper alloy substrate; the connecting grooves adopt a U-shaped groove-shaped cross section and are symmetrically distributed along the axis of the copper alloy substrate; the length of the connecting grooves is 1/5-1/2 of that of the copper alloy substrate; the inner surfaces of the connecting grooves are both distribute with aluminium alloy lining layers; and the thickness of the aluminium alloy lining layers is 1/4-3/4 of that of the connecting groove side wall; and the preparation method comprises four steps of copper alloy substrate prefabrication, connecting groove pre-processing, aluminum lining layer positioning, connecting groove diameter expansion and connecting groove fine processing. By virtue of the aluminum alloy high-voltage cable aluminum copper composite terminal and the preparation method thereof, the connecting structural strength, the impact resistance performance, the corrosion resistance performance and thehigh temperature resistance performance between the terminal and the cable can be improved effectively, so that the mechanical structural strength of the terminal is highly improved; and in addition,the overload capacity of the terminal is improved effectively, and current distribution uniformity is improved, thereby highly improving reliability and operational stability of the power cable connection operation.