The rectangular permanent-magnetic chuck is the auxiliary fitting of various kinds of plain surface grinder, universal tool grinder and electro machining. Machine too etc. According to the structure, it can be classified as ordinary permanent-magnetic chuck, fine-pole permanent-magnetic chuck, single-inclination permanent-magnetic chuck and double-inclination permanent-magnetic chuck. The rectangular single-inclination and double-inclination permanent-magnetic chuck is the permanent-magnetic chuck with sine bar positioning device. Except having application s of common permanent-magnetic chuck, they can be used for grinding various kinds of ferromagnetic work piece with single angle or composite angle. They can also be used as common sine bar fixture.