The invention relates to a preparation method of an aluminum oxide dispersion copper composite material. The aluminum oxide dispersion composite material is composed of the following components in percentage by weight: 18.6-23.4% of Al2O3, 1.6-2.1% of MgO, 0.6-1.1% of SiC and the balance of Cu. The preparation method comprises the following steps: proportioning, ball milling, pressing, sintering and heat treatment. The heat treatment process comprises the following steps: preheating treatment, conditioning treatment, refrigeration treatment, aging treatment, quenching treatment, secondary aging treatment, secondary refrigeration treatment, secondary conditioning treatment and grinding treatment, thereby greatly enhancing the strength of the composite material.