Disclosed is a method for scanning and processing an image using the error diffusion screening technology, comprising: (1) scanning each pixel Mi of an nth line in an original image one by one and then storing a scanning result of the pixel Mi to an ith storage location; and (2) processing the stored result of the pixel Mi by using error diffusion and scanning pixels of an n+1th line in the original image until all pixels of the nth line have been processed and all pixels in the n+1th line have been scanned and stored, wherein once processing for the pixel Mi is completed, a scanning result of a pixel of the n+1th line is stored to the ith storage location previously occupied by the pixel Mi. Based on the method, the capacity for storing is only required to be able to store the data of one line in an image in the scanning direction, which saves the storage for bidirectional scanning. The method can optimize the hardware used to implement error diffusion and improve the operating efficiency. Also disclosed is a system for achieving the method.