The current research and application status of calibration technologies and devices both in domestic and foreign developed countries are combed comprehensively. The fact that the calibration technology of digital watt-hour meters need to be deeply researched is indicated, and the metering system of digital watt-hour meter needs to be established. Challenges that how to accurately meter the actual electrical energy and calibrate the watt-hour meters because of the non-linearity, fluctuation and randomness of the electrical loads need to be overcomed. Finally, the future development trends of calibration technologies are presented.