A high hardness, high thermal conductivity and low expansion coefficient Al-Cu-CNT material and a preparation method thereof are disclosed, the high hardness, high thermal conductivity and low expansion coefficient Al-Cu-CNT material is characterized in that: the high hardness, high thermal conductivity and low expansion coefficient Al-Cu-CNT material is prepared from Al powder, Cu powder and CNT; the preparation method is as follows: first, the Al powder, the Cu powder and the CNT are uniformly mixed and dried for high-energy ball milling for mechanical alloying, ball-milled powder is pressed into blocks, a graphite-powder-coated sample is sintered for further fully mechanical alloying, and finally solution and aging treatment of the sintered sample is performed. The Al-Cu-CNT material has the advantages of uniform composition, high hardness, greatly-improved elastic modulus and thermal conductivity, low thermal expansion coefficient, and wide application prospect in the field of electronic packaging.