The invention discloses an image detection method and device. The method comprises the following steps that the gradient value response of each pixel point in an inputted image is calculated so that a gradient graph corresponding to the image is generated; a corresponding gradient integral graph is established according to the gradient graph; suspicious are selected through screening by using the gradient integral graph and location information of the suspicious areas is recorded; connectivity judgment is performed on the suspicious areas according to the location information of the suspicious areas; and the image is determined to be a mosaic image if connectivity judgment of the suspicious areas is passed. According to the method, the detection precision can be enhanced, and the probability that the rectangular areas in the image are misjudged as mosaics can be reduced.