The utility model discloses a comprehensive instrument detection device for a direct-current transmission valve cooling system, which comprises a temperature instrument detection unit, a pressure instrument detection unit, a liquid level instrument detection unit, a conductivity instrument detection unit and a flow instrument detection unit and further comprises a PLC (Programmable Logic Controller) control system and an upper computer, wherein the temperature instrument detection unit, the pressure instrument detection unit, the liquid level instrument detection unit, the conductivity instrument detection unit and the flow instrument detection unit communicate with the PLC control system; and the upper computer is connected with the control system by an optical fiber. The device can comprehensively detect and analyze accuracy of various instruments of the direct-current transmission valve cooling system, raises a system management level of valve cooling equipment, improves the risk precontrol capability, and provides scientific data bases for establishment of archives of on-line monitoring instrumentation of the valve cooling system and development of detection standards during detection and analysis.