The invention discloses a calibration method and device used for a laser processing system. The calibration method includes the steps that firstly, a lens in a galvanometer is controlled to be adjusted according to a calibration picture which is edited in advance, a laser device is driven, a laser beam generated by the laser device is made to penetrate through the galvanometer, and the calibration picture is etched on marking paper which is placed on a processing platform in advance; secondly, an image, photographed by a camera, of the processing platform is obtained, and the image includes the calibration picture; thirdly, distortion correction is conducted according to the image and the calibration picture etched on the marking paper, and the corresponding relation between an image coordinate system and a galvanometer coordinate system is obtained. According to the calibration method and device used for the laser processing system, distortion correction is achieved through the calibration picture on the marking paper, a target does not need to be used, cost is saved under the premise that precision is ensured, and the calibration operation is simplified.