Abstract: A terminal voltage control system with a generating voltmeter （GVM） for the single ion accelerator was designed. The principle of the control method was analyzed. The circuit consisting of a notch filter, a pass-filter, a rectifier filter, a band filter and an error amplifier was designed and made. The notch filter was designed in TT-type with the notch frequency of 50 Hz. The band filter was designed in asymmetric type with the band frequency of 35 Hz and band width of 50 Hz. The output voltage of the controlling circuit was set to 0-10 V which controlled the corona discharge current. The instability of the terminal voltage is tested to be less than 1%.