Electric energy meter field calibrator is a relatively mature product in the market currently, and it is applied in various transformer substations and various power supply departments. These departments need to use electric energy meter field calibrator to calibrate error of electric energy meter, besides, they need an instrument to measure secondary voltage drop of PT, what’s more, they also need to measure secondary load of PT and CT. However, traditional field calibrator does not have these functions, thus, special PT secondary voltage drop meter needs to be purchased for measurement. In this paper, an instrument is designed which can integrate electric energy meter field calibrator and PT secondary voltage drop meter together, which can not only save social resources, simplify work links of staff of power supply departments, but also improve work efficiency, thus, it has very important social significance and economic value. As it is proven in practice that the design of electric energy meter and PT secondary voltage drop comprehensive tester is feasible, and has obtained the approval of users.