This article describes the small synchronous generator excitation control device characteristics and working principle is proposed based on fuzzy control of excitation regulator device on-site test method. Phase compound excitations with voltage corrector by the way of magnetic amplifier were used in excitation devices. The generator terminal voltage, load current and power factor and other parameters were adjusted by fuzzy control through automatic control phase compound excitation transformer. For separate generator, the major factor of terminal voltage change was caused by the change of reactive current, in order to keep constant voltage generator excitation current mast be adjusted. At the end of the paper the problems and countermeasures in the course of debugging process were analyzed.