1. A calibration method of a touch screen, wherein the touch screen comprises a display module and a sensor module, the calibration method comprising: receiving coordinate values of multiple display points shown on the display module; receiving coordinate values of multiple sensing points received by the sensor module, wherein the multiple sensing points are corresponding to the multiple display points, respectively, for forming at least four multiple correspondences; calculating a first set of calibration formulas according to the multiple correspondences; adjusting the multiple sensing points according to the first set of calibration formulas; and calculating a second set of calibration formulas according to the adjusted sensing points.