Three-way valve, a specific equipment installed in the smoke gas pipeline and controlled by solenoid valve, can realize the free switching between "smoke gas evacuation" mode and "pipeline conduction" mode. All operations of valve plate are supervised by in-place detection switches, so as to achieve good sealing performance and reliable operation. It can be interlocked with the DCS system to realize automatic venting in various emergencies. The operating room can receive the valve plate in-place signal to realize closed-loop feedback.