The embodiment of the invention discloses a method and a device for balancing neutral point potential of a three-level converter for APF (accurate position finder), wherein the method provided by the embodiment of the invention comprises the following steps of: adding a balance control quantity to the neutral point current according to a SVPWM (Space Vector Pulse Width Modulation) algorithm, so that the primary charge of the neutral point can be neutralized by the charge injected by the neutral point current; then correcting a primary action time of a switch according to the balance control quantity obtained by calculating to achieve the purpose for compensating the deviation of the neutral point potential, and therefore the shortage of the prior art in the system complexity and high system power consumption which are caused by increasing switch elements of the system for solving the problem of neutral point potential balance when a three-level converter is applied to APF is solved, the three-level converter can be applied to the APF, the voltage grade of the APF is reduced, and the compensation effect of the APF is enhanced.