The application of a long-short composite pulsed laser in aluminum damage is explored. The influences of the reflectivity of material surface and the laser-material-coupling coefficient on damage mechanism are also discussed based on the thermal effect in laser-material interaction. The impact pressure and damage time of a short pulsed laser on aluminum and the thermal effect of a long pulsed laser irradiation on 2A12 aluminum are numerically calculated. A long-short composite pulsed laser irradiation experimental system is designed. The results show that the designed long-short composite pulsed laser can be used to damage 2A12 aluminum effectively and rapidly. Moreover, the damage effect is superior to that by the single long or short pulsed laser, and the damage time is effectively reduced.