In manufacturing industries such as automobile, home appliance and engineering machinery, etc, for the sheet metal uncoiling production line, the magnetic chuck used for steel plates stacking and conveying is the essential and important component, the usability and service life of which directly affect the normal operation of the whole production line. The new type of strong permanent magnetic chuck exclusively used for steel plates stacking and conveying developed by our company, works with permanent magnetic force, which is strong and it operates conveniently. Being the ideal magnetic products for sheet metal conveying, it can hold up steel plates of δ0.5—2.5mm with an air gap or non magnetic block of δ10mm, and can convey normally with δ7mm.