The invention belongs to the technical field of sewage purification, and particularly relates to a magnetic flocculation water deep-purification system. The system is composed of a sewage treatment part, a water-sludge separation part and a magnetic powder recovery part, wherein the water-sludge separation part comprises a separating tank, and a sludge collection device is arranged in the separating tank and comprises a permanent magnet turnplate and a discharging mechanism. The system can accelerate water-sludge separation by means of the magnetic property of magnetic powder, has a high treatment capacity and a good treatment effect, and is suitable for large-scale industrial application.