The invention discloses a wafer clamping device. Clamping pieces are arranged on a rotary chuck, the clamping pieces are composed of magnetic rotors, stators and screw rods, screw pairs are formed by the rotors and the screw rods, the power-on sequence of power-on currents in a plurality of sets of coils of the stators is controlled through a control unit, a magnetic field with rotating changes is formed, the rotors are driven to do rotating and lifting motion along the screw rods between the lower technology height and the upper wafer taking and placing height, check blocks on the rotors are driven to rotate between the angle of clamping a wafer and the angle of releasing the wafer, the wafer is clamped or released, the problems that due to the fact that the distance between the clamped wafer and a clean gas spraying device on the chuck is too large, the back face of the wafer cannot be effectively protected in the technology process can be effectively solved, and the back face of the wafer is prevented from being contaminated by chemical liquid. Meanwhile, enough operation space can be reserved for a mechanical arm for grabbing the wafer from the back face of the wafer when the wafer is taken and placed, and reliability of the wafer taking and placing action is improved.