As the key device of sub module of converter valve,IGBT is of great practical significance to improve the reliability of the converter valve by studding the anti-short circuit ability of IGBT.Based on the operating mechanism of modular multilevel converter valve,this paper proposes an IGBT short circuit test circuit and system of sub module of converter valve.A comprehensive assessment of the transient stress by short fault and the steady stress of the converter valve is achieved.The validity of test circuit and system is verified by proposing a test platform.