To investigate the extra-long fatigue properties of aluminum die casting materials, fatigue tests were conducted on two type of aluminum die casting materials. One type is Al-Si-Cu die casting alloys (ADC10-T5) and the other is Al-Si-Mg die casting alloys (AC4C-T6). In the case of AC4C-T6,the fatigue fractures were caused by shear type crack and fatigue strength decreased along with the increased along with the increase of the number of cycles. In the case of ADC10-T5,the fatigue fractures did not occur, that is, fatigue strength did not decrease along with the increase of the number of cycles.