The invention relates to a parallel transmitting and computing method and a system of two-dimensional image data. The method comprises the following steps: setting the width of an image to be processed as img_w, the width of a computing window as wnd_w and the height as wnd_h, wherein m*n computed results can be obtained each time at the computing window, and allocating an on-chip buffer region with the width of col_w and the total capacity of col_w*(wnd_h+n-1)+img_w for image processing, wherein col_w=wnd_w+m*2-1; at a T unit moment, transmitting the two-dimensional region reference data of the image to be processed required by computation for the first time to an on-chip buffer; and at a T+1 unit moment, obtaining a corresponding computed result of the time according to the reference data in the current on-chip buffer, and meanwhile, transmitting the reference data required by the computation for the next time to the on-chip buffer. The scheme realizes the parallel transmission and computation of two-dimensional images when in line-crossing processing, thereby the processing efficiency is improved.