In order to solve the problem of the existing calibration device of DC total electric field strength measuring instrument, such as poor controllability, low accuracy, and unable to meet the standard requirements to carry out the calibration work of DC total electric field strength measuring instrument, the optimization researches of calibration system of DC total electric field strength and ion current density measuring instrument are carried out, the technical advantages of the optimized calibration system are analyzed, and the development is carried out test analysis and verification. The results show that the optimized calibration system can not only meet the requirements of the standard, but also have the comprehensive function of calibrating the ion current density meter, which improves the convenience of calibration. Moreover, the calibration system uses a circular flat plate design to make the electric field distribution more uniform and isotropic, which effectively improves the calibration accuracy.