The invention relates to a high-temperature superconducting cable high-voltage testing system and method, in particular to a high-temperature superconducting cable alternating current tolerance testing system and method. A conventional power cable is connected with a tested high-temperature superconducting cable in an end-to-end mode to form a closed loop. A transformer is used as a voltage source to lift the voltage to ground of a superconducting cable wire core. A current booster is used as a current source to form a large current in an induction mode in a whole closed loop through a conventional power cable section according to the mutual inductance principle. Given that the cables are large capacitive load, a compensation reactor is arranged to balance the capacitive current in the loop, so that the voltage source works under an underloading situation far below the nominal output, the number of the front ends of the current booster is reasonably arranged, and accordingly long-time operation of the whole testing system is guaranteed, and a high-temperature superconducting cable long-time high-voltage large-current alternating current tolerance test is carried out. The whole system is simple in structure and easy to implement, and cost is saved.