Abstract: The microstructure of 2618 aluminum alloy extruded state after different solution treatment was observed and analyzed. The hardness changes before and after solution treatment were measured. The results show that the extruded 2618 aluminum alloy is mainly composed of α-Al, Al₉FeNi, Al₇Cu₂Fe and small amount of Al₂Cu phases. In solution treatment at fixing temperature+temperature rise, the hardness of 2618 aluminum alloy increases first and then decreases with the increase of solid solution temperature. At 547 ℃, the hardness of 2618 aluminum alloy is increased by 6.1% compared with that of constant temperature solution treatment, and no grain coarsening and over-firing occur in the alloy. In solution treatment at fixing temperature+temperature rise+cooling and heating cycle, with the increase of cycle times, the hardness of 2618 aluminum alloy also increases first and then decreases. The maximum value is reached in two cycles of solid solution treatment. The hardness of 2618 aluminum alloy treated with fixing temperature solution is increased by 14.5%. There is no grain coarsening and over-burning in the alloy. Solid solution treatment of fixing temperature+temperature rise or fixing temperature+temperature rise+cooling and heating cycle can effectively improve the solid solution effect and mechanical properties of 2618 aluminum alloy.