Laser peening (LP) is conducted on aeronautical 2024-T351 aluminum alloy under different temperatures, and the influence law of temperature on its surface mechanical property is studied. In combination with the microstructure analysis, the strengthening mechanism of 2024-T351 aluminum alloy treated by warm laser peening (WLP) is revealed. The results indicate that the micro-hardness of aeronautical 2024-T351 aluminum alloy increases with the increment of peening temperature. The dispersion strengthening effect makes the amplitude of residual compressive stress induced by 120 ℃-WLP much higher than that by room-temperature LP.