A long-length imaging method based on digital radiography, a digital radiography device, an image processing system and a computer-readable memory medium to implement the method. The long-length imaging method comprises the following steps: A. determining a part of interest of an anatomy of an object; B. determining imaging parameters of digital radiography based on the part of interest, the imaging parameters at least including a plurality of specified positions of imaging components, wherein the plurality of specified positions are configured to capture X-ray images including the part of interest of the anatomy of the object; and C. generating a long-length image in relation to the part of interest of the anatomy of the object based on the captured X-ray images.