According to the shortages of the existing high voltage（HV） energy measuring system of electric power system， a scheme of HV Watt-hour meter to directly measure the HV energy is provided. The power energy measuring units， in which signals are acquired by low voltage（LV） current transformer and HV capacity potentiometer， works at the equipotential state of phase A and phase C. And power energy synthesis unit works on the potential of phase B. All units are insulated and connected by optic fibres. Power supplies of all units are coupled through HV capacity directly. The HV Watt-hour meter has the characteristics of favorable anti-electricity-stolen function， definite accuracy grade， avoiding ferromagnetic syntony， low volume， etc. The structure and principle of the meter are introduced. The sensors， hardware and power supply of the HV Watt-hour meter are discussed. At last， the errors of HV Watt-hour meter and test results of the sample meter are analyzed.