A robot positioning method includes the following steps. A optical sensing device is configured at a front end of a robot. Then, the optical sensing device captures a calibration plate image, and a relative position of the optical sensing device with respective to a calibration plate is calculated according to a Bundle Adjustment. A robot calibration method includes the following steps. An optical sensing device is driven to rotate around a reference axis of a calibration plate, so as to calculate a translation matrix between the calibration plate and the robot, and the optical sensing device is driven to translate along three orthogonal reference axes of the calibration plate, so as to calculate a rotation matrix between the calibration plate and the robot.