Abstract: In order to track the plasma rapid change in the vertical displacement, an H-bridge quick response power supply based on IGBT has been developed, rating of the power supply parameters for +500 V/+3 kA. Due to the structure and control strategy, the old quick response power supply has some deficiencies such as IGBT turn-off overvoltage, low working frequency, wide pulse voltage of uncontrolled flyback process. Aiming to solve these deficiencies, firstly, a new H-bridge quick response power supply redesigns the structure to reduce the power of the parasitic inductance, which brings down the IGBT turn-off overvoltage. Secondly, through changing the control mode of power supply, the working frequency of the power supply is two times the IGBT switch frequency, and the frequency of the power supply output voltage is increased, equivalent to improve the fast response ability of the power supply. At the same time, a kind of controllable flyback mode is designed, which changes the flyback circuit with IGBT to make the flyback process under control. Tested by the experimental study, the response time of the power supply is 125 s. The power supply has a quick response when the displacement of plasma changes, ensuring the normal discharge of tokamak, and with the new freewheeling control mode, the wide voltage pulse will not happen again, thus the output voltage can effectively track the given voltage change.