The invention relates to a low-voltage ride-through test system for a 3000 kVA-grade high-capacity frequency converter. The system is used for the low-voltage ride-through test on high-voltage and high-capacity frequency converters. The system comprises a voltage sag generator arranged on the power supply side of a frequency converter and used for simulating the voltage sag during actual production; a test monitoring system used for acquiring relevant data signals from the power supply side and the load side of the frequency converter, and monitoring test data; and an adjustable simulation load arranged on the load side of the frequency converter, and used for simulating the actual load of the load side of the frequency converter. The maximum simulated capacity of the simulated load is 3000 kVA. The rated voltage of the simulated load is 6 kV. Compared with the prior art, by means of a high-voltage and high-capacity simulation load, the problem in the prior art that a motor connected with the load side of the frequency converter cannot run normally in the on-load state so as to disable the test during the shutdown maintenance periods of a thermal power plant and a transformer substation can be solved. The system is convenient to operate.