The technology research about electric vehicle charging , especially DC power metering , is in full swing. To the current situation that there are few devices for off board charger energy metering, this paper introduces an off board charger detecting device for virtual load verification. The device has maturity function, adopts an integrated design in structure, and the circuit is equipped with Android carrier by CPU as the central control, driving voltage and current isolation output. Among them, the voltage source part adopts the combination scheme of digital-to-analog converter and high-precision resistor network reverse tube module, the current source part adopts the combination scheme of digital-to-analog converter and low-end sampling and feedback module. Through on-site virtual load verification of off board DC charger , the accuracy and feasibility of the verification device are verified by comparing the experimental results of the on-site tester of the charger and the device.