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