Motor load shedding test system and method under test platform

The invention provides a motor load shedding test system and method under a test platform, and the system comprises a weak power grid which collects the current of each power branch under the test platform; a first test branch, receiving the power flow or generating the power flow after being started; a second test branch, receiving the power flow or generating the power flow after being started; the first test branch comprising a first frequency converter, and the second test branch comprising a second frequency converter; a gearbox, used for receiving the power flow of the first test branch or the second test branch; a control module, which sends a first load switching instruction to the first frequency converter and controls the first frequency converter to jump a first power change amount, the control module sends a second load switching instruction to the second frequency converter and controls the second frequency converter to jump a second power change amount, and the first power change amount and the