The present invention discloses an image acquisition method, device and a radiography system. Said image acquisition method comprises a determination step: determining the starting position, the ending position of a region of interest, and the value of overlap of the region of interest in the two adjacent sub-images； a calculation step: calculating the number of the sub-images required to be captured, the component of field of view at the direction of tube movement as well as the positions of the tube (1) and the detector (4) corresponding to each sub-image based on the starting position and the ending position of a region of interest and the value of said overlap； a capturation step: moving the tube and the detector to each position and capturing the region of interest to obtain several sub-images at said positions； a pasting step: pasting the several sub-images together to form an image of the said region of interest. Said image acquisition device comprises a determination unit, a calculation unit, a capturation unit, and a pasting unit. Said radiography system comprises an image acquisition device. The images acquired by the technical solution of the present invention are more accurate.
