The invention discloses a gear tooth clamping device. The device comprises a gear tooth alignment plate for aligning the position of a gear tooth; the gear tooth alignment plate is provided with a center line and at least two graduation lines perpendicular to the center line; and the gear tooth alignment plate is provided with a gear tooth fixing structure for fixing the gear tooth and a rotationdriving mechanism for driving the gear tooth fixing structure to rotate so as to adjust a measurement point on the tooth surface of a gear to make the measurement point located at a set position. Theinvention also discloses a tooth surface residual stress measuring method using the above gear tooth clamping device. With the gear tooth clamping device and tooth surface residual stress measuring method of the invention adopted, focusing can be performed quickly and conveniently; a camera light path or a focusing probe will not be blocked and interfered, any position of the tooth surface can bemeasured; a diffraction ring light path will not be blocked by other gear teeth, so that a measurement result is more stable; a position point satisfying a condition that kd<=R is selected as the measurement point, and therefore, measurement accuracy can be effectively improved; and, the gear tooth clamping device is adopted, so that a gear tooth alignment pose can be cut off quickly, and therefore, the accurate positioning of the measurement point can be realized.