Abstract: DC circuit breaker is the main means to clear the faults in VSC-HVDC power grid. Before action of the hybrid DC circuit breaker, the IGBT in the transfer branch is in a state of zero voltage and zero current. When the current of the transfer branch begins to rise, and once the voltage overshoot of collector-emitter produced in the forward recovery process of IGBT meets the IGBT's over-current monitoring criterion, the protection will malfunction, consequently reducing the operating reliability. Aiming at the forward recovery phenomenon of IGBT, a high-current turn-on experimental platform of IGBT is built to obtain the IGBT’s collector-emitter voltage waveforms corresponding to different current waveforms. Based on the staged mathematical fitting, an I-U mapping relationship that reflects the forward recovery characteristics of the IGBT is established. Compared with the experimental results, the relative error of peak collector-emitter voltage is less than 10%, and the duration relative error of over-current monitoring threshold voltage is less than 15%. The model can help to reasonably formulate the over-current monitoring criterion of IGBT used in DC circuit breaker.