Shunt active power filter is an important part of power grid in harmonic control.Neutral point clamped(NPC)three-level shunt active filter is applicable for current harmonic compensation in high-power, high-voltage situation. To address the problem of Neutral-point Potential Fluctuation in traditional NPCthree-level shunt active filter,a structure of NPC Three-level Shunt Active Filter with Neutral-point Potential Fluctuation Self-eliminating is proposed,a controlled voltage source is stringed into a controlled voltage source between DC side neutral-point and Three-phase bridge arm neutral-point,which is used to give a real-time compensation to Neutral-point Potential Fluctuation by control the size of output voltage of controlled voltage source. Simulation results show that theproposed structure of the new Shunt Active Filter can effectively eliminate the Neutral-point Potential Fluctuation,and the system has good dynamic performances,and has high practical value.