A system for controlling a dual-mode brake for a locomotive, comprising a relay valve in communication with a train pipe, and an pressure-equalizing device, of which one end is in communication with a main pipe and another end is in communication with an inlet port of the relay valve, characterized in that the system further comprises: a mode-switching valve connected between the relay valve and the pressure-equalizing device, a backup pressure regulating valve in communication with the main pipe, an electro-interlock cut-out cock in communication with an outlet port of the backup pressure regulating valve, and a brake controller; wherein the mode-switching valve is provided with a first inlet port, a second inlet port and an outlet port, the first inlet port of the mode-switching valve is in communication with an outlet port of the pressure-equalizing device, the second inlet port of the mode-switching valve is in communication with an outlet port of the electro-interlock cut-out cock, and the outlet port of the mode-switching valve is in communication with an equalization inlet port of the relay valve; and wherein the inlet port of the electro-interlock cut-out cock and the outlet port of the electro-interlock cut-out cock are in communication with each other in case of the electro-interlock cut-out cock being triggered, and are cut out from each other in case of the electro-interlock cut-out cock being not triggered; wherein the brake controller is configured to enable the outlet port of the mode-switching valve to be in communication with the second inlet port of the mode-switching valve in case of the electro-interlock cut-out cock being triggered, and configured to enable the outlet port of the mode-switching valve to be in communication with the first inlet port of the mode-switching valve in case of the electro-interlock cut-out cock being not triggered. characterized in that the system further comprises: a mode-switching valve connected between the relay valve and the pressure-equalizing device, a backup pressure regulating valve in communication with the main pipe, an electro-interlock cut-out cock in communication with an outlet port of the backup pressure regulating valve, and a brake controller; wherein the mode-switching valve is provided with a first inlet port, a second inlet port and an outlet port, the first inlet port of the mode-switching valve is in communication with an outlet port of the pressure-equalizing device, the second inlet port of the mode-switching valve is in communication with an outlet port of the electro-interlock cut-out cock, and the outlet port of the mode-switching valve is in communication with an equalization inlet port of the relay valve; and wherein the inlet port of the electro-interlock cut-out cock and the outlet port of the electro-interlock cut-out cock are in communication with each other in case of the electro-interlock cut-out cock being triggered, and are cut out from each other in case of the electro-interlock cut-out cock being not triggered; wherein the brake controller is configured to enable the outlet port of the mode-switching valve to be in communication with the second inlet port of the mode-switching valve in case of the electro-interlock cut-out cock being triggered, and configured to enable the outlet port of the mode-switching valve to be in communication with the first inlet port of the mode-switching valve in case of the electro-interlock cut-out cock being not triggered.