The embodiment of the invention provides a DC blocking method and system under isolated island low power and a DC station control cabinet, relates to the technical field of the power systems, and solves a problem that it possibly generate parallel resonance and cause influences on the safety and stability of a power grid in a isolated island low-power operation condition in the prior art because of a decrease in the number of generating sets and a decrease in the short-circuit capacity of an AC system. The method comprises steps of: obtaining bipolar running state quantity, bipolar total power and isolated island state signal quantity; and blocking a bipolar or switching a DC station control system according to the bipolar running state quantity, the bipolar total power, the isolated island state signal quantity and isolated island low-power blocking state signal quantity. The method and system are applied to the control of isolated island low power blocking DC.