An image scanning method applied in an image scanning device capable of scanning a card. Record background values at the time of a card being without being in a scanning channel, and the background values recorded at the time of the card being without being in the scanning channel are regarded as preset values. Before the card is scanned, check whether the background values in the scanning channel conform to the preset values. Drive the card to move a distance Y. Check whether the background values in the scanning channel conform to the preset values. Preset a preset movement distance, check whether a movement distance of the card or a distance of accumulated movements of the card exceeds the preset movement distance. Display that the card is stuck. Stop checking and proceeding with an image calibration. Start scanning the card. Complete scanning the card and withdraw the card.