Indirect connected DC energy meter is the indispensable apparatus for trade settlement in automobile charging, rail transit and other fields. It usually works with DC shunt. This paper analyses separate and integral calibration tests of this type of meter, and draws a conclusion that the error is greatly affected by the lead resistance and input impedance. It is proposed that the input impedance of DC small signal should be included in the type evaluation items of this type of meter, and the lead error should be minimized to ensure the accuracy of DC electric energy measurement.