A method for enhancing scan resolution, suitable for the application of a scanner with a sensor. The range that a detecting cell in the sensor can detect is the original pixels with a predetermined number. The scanned result of the detecting cell is called the scanned pixels. In the method for enhancing scan resolution, a smooth image region is scanned to obtain a smooth image data. The smooth image region includes at least the above original pixels with the predetermined number. The smooth image region has a uniform brightness. According to the smooth image data, the scanned pixels obtained from scanning the document are processed.