The method of error distribution is used in the management and configuration of high voltage power metering device to control the overall error limits indirectly. This paper introduces the structure and principle of the direct measurement system of the whole error of high voltage power metering device. The whole error of a set of 10kV and 100A high voltage power metering device is directly measured by the system. And the measurement results are compared with the calculation results of the comprehensive error method. The results show that the system can accurately measure the whole error of high voltage power metering device. Compared with the method of comprehensive error calculation, it has the characteristics of direct, fast and accurate and can reduce the uncertainty of the error of high voltage power metering device in actual operation.