A magnetic bar self-rotation type permanent magnet filter is disclosed. A magnetic chain is driven by a motor drive mechanism to periodically reciprocate and to enter the liquid in a tank body used for storing cold rolling cooling liquid so that metal dust in the cooling liquid is adsorbed. A decontamination mechanism is disposed on the magnetic chain mechanism and is in contact with a decontamination segment, above the liquid level, of the reciprocating magnetic chain in a manner that the decontamination mechanism and the plane where the upper surface of the magnetic chain is are perpendicular to each other or arranged with a certain included angle, and in this process, each magnetic bar moves in a direction perpendicular to the length direction of the magnetic bar and rotates itself at the same time to scrape metal dust off the magnetic bar. Magnetic bar deformation or damage caused by rigid contact with the decontamination mechanism in a magnetic bar movement process, and device failure breakdown caused when the decontamination mechanism is stuck in the magnetic bar transmission chain can be prevented. In addition, the overall size of the device can be greatly reduced, the operation speed and follow-up effect of the magnetic chain mechanism are significantly improved, and the device has wider applicability.