An interlocking control device for a multiple-unit safety circuit, comprising: a protective grounding switch control branch which comprises: a pantograph rising pneumatic circuit cut-off valve, a protective grounding switch turn-off pneumatic circuit cut-off valve and a protective grounding switch turn-off solenoid valve which are connected in series; wherein keys for a high-voltage equipment cabinet and an external power supply cabinet are located in a key box; a cover of the key box is mechanically locked by means of a pantograph rising pneumatic circuit cut-off valve and a protective grounding switch turn-off pneumatic circuit cut-off valve; when high-voltage equipment of a multiple-unit train is under inspection and maintenance or is powered by an external power supply, a protective grounding switch is turned on, a cock of the pantograph rising pneumatic circuit cut-off valve and a cock of the protective grounding switch turn-off pneumatic circuit cut-off valve are rotated to open the cover of the key box; simultaneously, the protective grounding switch control branch is disconnected, and the protective grounding switch turn-off solenoid valve connected in series in the protective grounding switch control branch is powered off to maintain the protective grounding switch in an on state; characterized by a first pantograph interlocking control branch which comprises: a normally-closed contact of the protective grounding switch and a coil of a pantograph rising relay which are connected in series, wherein the normally-closed contact of the protective grounding switch is opened and the coil of the pantograph rising relay is powered off when the protective grounding switch is turned on, such that a pantograph is unable to rise. a protective grounding switch control branch which comprises: a pantograph rising pneumatic circuit cut-off valve, a protective grounding switch turn-off pneumatic circuit cut-off valve and a protective grounding switch turn-off solenoid valve which are connected in series; wherein keys for a high-voltage equipment cabinet and an external power supply cabinet are located in a key box; a cover of the key box is mechanically locked by means of a pantograph rising pneumatic circuit cut-off valve and a protective grounding switch turn-off pneumatic circuit cut-off valve; when high-voltage equipment of a multiple-unit train is under inspection and maintenance or is powered by an external power supply, a protective grounding switch is turned on, a cock of the pantograph rising pneumatic circuit cut-off valve and a cock of the protective grounding switch turn-off pneumatic circuit cut-off valve are rotated to open the cover of the key box; simultaneously, the protective grounding switch control branch is disconnected, and the protective grounding switch turn-off solenoid valve connected in series in the protective grounding switch control branch is powered off to maintain the protective grounding switch in an on state; characterized by a first pantograph interlocking control branch which comprises: a normally-closed contact of the protective grounding switch and a coil of a pantograph rising relay which are connected in series, wherein the normally-closed contact of the protective grounding switch is opened and the coil of the pantograph rising relay is powered off when the protective grounding switch is turned on, such that a pantograph is unable to rise.