The ultra-high voltage (UHV) shunt reactor is an important electrical equipment in UHV AC transmission engineering. In actual operation, the overvoltage waveform invading the UHV shunt reactor is mostly non-standard impulse voltage waveform, which differs significantly from the standard waveform used in insulation tests of current power equipment. Establishing a voltage distribution characteristic detection system for shunt reactor windings under arbitrary waveform is a key technology in insulation tests, with the core being the generation of arbitrary waveform voltage.This paper proposes a measurement system for voltage distribution of UHV shunt reactor windings under arbitrary voltage waveforms. By fitting the voltage waveform, combining the arbitrary waveform signal generator with the power amplifier, the method of injecting arbitrary voltage waveforms such as lightning impulse full wave, lightning impulse chopped wave, standard operation full wave, non-standard operation full wave, fault wave, etc., into the test device is realized. Under the premise of ensuring accuracy, damage to the winding coils and supporting structures of the reactor products is reduced. Finally, experiments were conducted on a laboratory prototype and two actual products of UHV shunt reactors, validating that this system's measuring device has accuracy, low experimental grade, wide measurement range, and broad frequency response, providing a feasible solution for measuring the transient voltage distribution characteristics, which is useful for guiding insulation estimate.