The invention discloses a nonmagnetic material workpiece clamping device and the method used for a surface grinder. The device comprises a ring pedestal and at least three fasteners; the ring pedestal is made of ferro-magnetic material, and is formed with at least three threaded holes; the fasteners are fitted with the threaded holes, and used for fixing the nonmagnetic material workpiece placed in the ring pedestal. In the invention, the magnetic pedestal can solve the problems of clamping a nonmagnetic material workpiece on a surface grinder; the ring structure can place a square, a circular or a polygonal workpiece; the application of the threaded holes and threaded rods can apply forces to the workpiece to be clamped from a plurality of directions, thereby improving the stability of the workpiece in grinding process, and reducing the demands to the shape of the workpiece greatly at the same time. In addition, the device disclosed by the invention achieves the advantages of small occupation space, convenient operation, time saving, labor saving and low cost.