The invention discloses a relay protection vector inspecting and testing device adopting a frequency-variable electronic voltage regulator. The device comprises a boosting transformer, a filter, the frequency-variable electronic voltage regulator, a compensation capacitor group parallelly connected on the secondary side of the boosting transformer and a tested product parallelly connected with thecompensation capacitor group, and the filter and the frequency-variable electronic voltage regulator are sequentially connected on the primary side of the boosting transformer serially. By adopting atriphase frequency-variable electronic voltage regulator, frequency and voltage can be regulated while detection of whether a testing system is intact in state or not, checking of whether the numberof input compensation capacitors is correct or not and guaranteeing of an inductive load being fully compensated by the compensation capacitors can be realized. Compared with a device adopting an electromagnetic induction voltage regulator, the relay protection vector inspecting and testing device has the advantages that mass is reduced by 80%, and the testing device is convenient to transport, flexible to move and free of being limited by a site; in a full-load state, power source current is reduced by 75%, maximum working current is 27A only, and output frequency is not limited by a tested power source; the testing device is sensitive to adjust, simple and convenient to operate and remarkable in economic benefit, and manufacturing cost is lowered substantially.