This paper presents an improved method for calibrating inductive voltage divider by double-equilibrium reference potential incremental calibration method, which combines a follower that can work at high voltage with a differential voltage measurement device to solve the influence of leakage current on the voltage ratio of the inductive voltage divider during the self-calibration process; by connecting a follower at the output of the reference voltage divider, the current of the differential measurement loop will not flow into the reference voltage divider to ensure the stability of the reference potential. The developed inductive voltage divider is self-calibrated at 400 V with a standard uncertainty of 1.5×10-9 for the ratio and 2.3×10-9 rad for the phase.