The present invention relates to a method and device for quality assurance of flat printed products. In the method, firstly, prints are put on bearing components; and secondly, at least one light source irradiation print and the bearing components are also included, wherein shooting of an image of at least one structural component with a print for the irradiated print is realized through at least one image recording device. In addition at least one structure component of the print, at least one structure component of the bearing component is also shot; and the geometric object of the bearing component is determined among at least one structure component. And then compared the practical value of at least one geometric object of the bearing component with the specified theoretical value for the geometric object, the ultimate comparison result is used for controlling reprocessing of the prints.