Abstract: In order to solve the problems of misalignment, failure and even damage of clamp ammeters in operation due to that the new energy power generation, grid connection and nonlinear load bring DC components to the AC power supply system, the disadvantages and applicability of traditional AC clamp ammeters were analyzed, and an AC/DC clamp ammeter for field calibration based on the Hall component DC compensation and a self-calibration technique was designed. The extended measurement uncertainty was evaluated. The relative uncertainty at all the selected AC/DC calibration points was within the range of 0.2% and the accuracy grade of the prototype was equal to and even better than 0.5 grades. The prototype was compared with traditional AC clamp ammeters through a test experiment. The results of the experiment indicated the capability of the designed clamp ammeter to make AC/DC measurement, which met the design requirements and showed its potential for application.