The invention discloses a method and device for image authentication. The method comprises the steps of 1, a matched image and an image secret key are obtained; S2, the matched image and the image secret key are converted into a corresponding gray scale single channel graph; S3, through an ORB characteristic extracting algorithm, extraction of image characteristics and matching are conducted on the converted matched image and image secret key; S4, whether an ORB characteristic detection is passed or not is judged, if yes, the step S5 is entered, and if not, matching fails; S5, template matching is conducted on the matched image and the image secret key, if matching succeeds, encoding succeeds, and if matching fails, encoding fails. According to the method and device for the image authentication, by combining the ORB characteristic detection and template matching, blind spots in image matching can be optimized, and the comprehensive image matching level can be improved.