This paper analyzes the causes of neutral point displacement voltage generation in 66 kV distribution network and proposes a method for inhibiting the neutral point displacement voltage based on an active regulation techniques. It compensates for the asymmetry of the unbalanced current due to the line parameters caused by injecting current into the neutral point, and combining with actual grid operating parameters, analyzes the relationship between the amplitude and phase of the injected current and the displacement voltage of the neutral point to determine the injected current. The state identification system method that injects constant frequency harmonic measurement signal to the grid is employed, which achieves effective suppression of neutral point displacement voltage by active inverter combining with voltage and current double closed loop control. Finally, the correctness and effectiveness of the proposed method is verified by using the Matlab/Simulink-based distribution network simulation experiment and actual physical experiment. This work is supported by Science and Technology Project of State Grid Corporation of China (No. SGMDTL00FCJS1800748) and Project of Science and Technology Department of Jilin Province (No. 20160307014GX).