The invention provides a current supply device, a power equipment vector testing device and a power equipment vector testing system. According to the current supply device, the power equipment vectortesting device and the power equipment vector testing system, existing parallelly-connected compensation capacitors are changed into a series compensation capacitor in a current supply device, since the resistance of a transformer is very small, the shown impedance is mainly reactance, and the reactance of a test loop can be reduced by connecting a capacitor in series in a test loop, therefore, the purpose of acquiring high test current by applying the same test voltage in the test period can be achieved; moreover, the impedance of the compensation capacitor is different from the impedance oftested power equipment, thereby avoiding the resonance caused by the same impedance during series connection, and being suitable for the vector test of a high-impedance transformer through the ingenious combination of the above means.