Sealing device

The invention discloses a sealing device. The sealing device comprises a shaft sleeve, an external ring, a magnetic field generating unit and a seal ring, wherein the external ring is used for the passage of the shaft sleeve; the magnetic field generating unit is arranged in the external ring and surrounds at the exterior of the shaft sleeve, and the magnetic field generating unit comprises an inner magnetic ring and an outer magnetic ring; at least one of the inner magnetic ring and the outer magnetic ring is a magnet; a clearance is reserved between the inner magnetic ring and the outer magnetic ring and is used for filling magnetic fluid; the magnetic field generating unit can generate a magnetic field to keep the magnetic fluid in the clearance; and the seal ring is arranged in the external ring and comprises an outer periphery and an inner periphery which are radially separated, the inner periphery of the seal ring is used for the passage of the shaft sleeve, one end of the innerperiphery of the seal rin