Abstract: Cracking failure behavior of hot stamping die was analyzed systematically, from the aspects of quality evaluation of die material itself, thermo-mechanical fatigue during service and stress corrosion of water channel.It is concluded that the cracking of insert material is caused by the combined action of thermo-mechanical fatigue and waterway corrosion.The corrosion pit (corrosion) in the upper half of the channel provides a breakthrough for brittle cracking.The waterway corrosion, especially formation of spot corrosion, forms a stress concentration under thermal stamping, which may form a crack source.