Abstract: According to the requirements of high robustness and positive and negative polarity controllability of the sampling circuit for bipolar charging power supply designed for a large capacity energy storage device, a positive and negative bipolar DC high-voltage isolation sampling circuit with isolation voltage ≥ 30 kV and conversion voltage fractional error ≤ 0.1% has been developed. The voltage/frequency and frequency/voltage conversion methods were adopted, integrated with optical fibers, transformer isolation and other measures, the positive and negative bipolar DC high voltage were isolated and sampled independently at the same time. The problems of the bipolar DC high voltage power supply, such as the voltage imbalance of positive and negative polarity, the incomplete isolation of ground wires between the control signal system and the high power system, and so on were solved. The EMI resistance of the power supply was improved. As the bipolar charging voltage output achieved ± 10 kV, the deviation of positive and negative polarity voltage is less than 0.1%. More than 100 chargers operated reliably and stably under the complex electromagnetic interference environment generated by discharge of the 18.3 MJ pulsed device.