Abstract: It is necessary to monitor in real time the cyanide concentration in cyanide-containing pulp during the detoxification treatment.The online monitoring device for cyanide-containing pulp pretreatment realizes the solid and liquid separation pretreatment for the pulp treatment process,reaches the level water quality automatic analyzer requires to monitor the water quality in pulp,and guides cyanide-containing pulp treatment.The paper mainly introduced the design principles,structures and working mechanism of the online monitoring device for cyanide-containing pulp pretreatment,and verified the device by practical operation in labs.Various filter media and related experimental parameters verified the working mechanism and the production practice feasibility of the online monitoring device for cyanide-containing pulp pretreatment.