Abstract: The present disclosure provides an image automatic correction method of a document camera, and the image automatic correction method includes steps as follows. An image is captured; at least one image feature value is extracted from the image, and whether an imaged picture has changed is determined according to the at least one image feature value of the image and at least one previous image feature value of a previous image; when the imaged picture has changed as determined, a focal length value is calculated, and whether the image needs to be rotated is determined according to the focal length value.