A digital ON/OFF capability checking device of a low-voltage DC switch is characterized by comprising a test power supply, a low-voltage protective switch, a control switch, a test object, a voltage transformer, a temporary setting wire, a setting contactor, a test-assisted switch, a load resistor, a load reactor, a current transformer and a control and data collection system. The device and method have the advantages including simple structure, convenient operation, high stability, high safety and high intelligent level.