Abstract: The early cracking failure occurred to a blanking die of YG8 cemented carbide in the course of use. The cracking reasons of the blanking die were analyzed by macroscopic observation, hardness testing, scanning electron microscope and energy spectrum analysis, metallographic inspection and so on. The results show that:due to the poor preservation of the blanking die material, the tungsten powder contacted with the air and oxidized; as a result of that, there were a lot of brittle η phase and reticular cracks in the structure, and the indexes of the strength and toughness of the material drastically reduced; the blanking die couldn't bear the working stress during use, and the early cracking failure occurred.