Abstract: A systematic in vestigation to the responses of specimens made of LY12 aluminum alloy subjected to different levels of pre-load and heated with different heating-rate is performed using a Glee ble-1500 thermal-mechanical material testing system. The near-tip metallurgra phics is also observed and analyzed. The investigation results show that both temperature and heating-rate play significant roles in the mechanical behavior o f LY12. For the same level of pre-load, an increase in heating-rate will increase both the yield and fracture temperature, and the high heating-rate induced inconsistence of local temperature accounts for the severe defect in the material and the failure of the meterial.