The present invention relates to a method for achieving boundary localization in a scanning apparatus, as well as to a scanning apparatus, which is capable of achieving intelligent judgement on boundary localization of the scanned file by means of this method, through an effective combination of optical, electronical and mechanical techniques. Said method comprises: a regular ribbon, a sensor module capable of detecting the ribbon, and the file to be scanned is placed between the ribbon and the sensor module; said sensor module first scans the ribbon information and stores it in the storage module of the scanning apparatus; said file to be scanned is placed between the sensor module and the ribbon, through the measured ribbon portion covered by the file to be scanned, the sensor is capable of deriving the boundary position of the file to be scanned by means of contrast measurement. With the scanning apparatus capable of achieving boundary localization.