Abstract: A method used to measure the burnthrough time of LY-12 aluminum targets irradiated by a 1-06μm free-oscillation long-pulse laser beam is described. Measruement techniques for ablated target parameters △m and h with electronic balance, metallograph and collector are also presented. The recession velocity and ablation velocity of targets have been experimentally obtained. For laser power I=10⁵ ～10⁷W/cm², the recession velocity ranges from 0.5m/s to 3.8m/s, and the ablation velocity between Ig/s and 8g/s.