The invention discloses a circuit and a method for measuring 
stray inductance of a current conversion circuit of a three-
level converter. The circuit comprises a first IGBT (
insulated gate bipolar transistor), a second IGBT, a third IGBT, a fourth IBGT, a first clamp 
diode, a second clamp 
diode, a first 
resonant capacitor, a second 
resonant capacitor, a first direct-current support 
capacitor, a second direct-current support 
capacitor, a laminated 
busbar, a direct-current power supply and a 
freewheel reactor. The method includes forming different 
freewheel circuits by the 
freewheel reactor; exerting double pulses to each corresponding IGBT; taking an average value of 
resonance current frequencies at a turn-on moment and a turn-off moment; and precisely computing the 
stray inductance of the current conversion circuit by an LC 
parallel resonance characteristic realized by the resonant capacitors and the 
stray inductance of the circuit. The circuit and the method have the advantages that actual operation is facilitated, the stray 
inductance of the current conversion circuit of the three-
level converter can be accurately measured, 
overvoltage levels of a power device under different current grades of the three-
level converter can be accurately controlled conveniently, and accordingly establishment of a 
system control strategy can be guided.