The invention provides a train set safety circuit interlocking control device. A protection grounding switch control branch comprises a pantograph rising gas circuit block valve, a protection grounding switch open gas circuit block valve and a protection grounding switch open solenoid valve connected in series. When a train set high voltage device is repaired and maintained or an external power supply provides power, the protection grounding switch is operated to be closed, the cock of the pantograph rising gas circuit block valve and the cock of the protection grounding switch open gas circuit block valve are rotated to open the cover of a key locker; the protection grounding switch control branch is disconnected, the protection grounding switch open solenoid valve serially connected in the protection grounding switch control branch is loss of power, and the protection grounding switch open solenoid valve is loss of power to enable the protection grounding switch to be kept to be closed; and the cover of the key locker is mechanically locked through the pantograph rising gas circuit block valve and the protection grounding switch open gas circuit block valve. When the high voltage device is repaired and maintained or the external power supply provides power, the protection grounding switch needs to be in a closing state, and the personal safety of a maintainer is protected.