Image processing method and device for a spliced panel and a spliced panel are provided. The image processing method includes calculating a horizontal stretch coefficient of the spliced panel according to a resolution of the plurality of display units, a sum of horizontal spliced-gap widths of the spliced panel and a horizontal pixel pitch of the plurality of display units; calculating a vertical stretch coefficient of the spliced panel according to the resolution of the plurality of display units, a sum of vertical spliced-gap widths of the spliced panel and a vertical pixel pitch of the plurality of display units; stretching an original image to be displayed by the spliced panel according to the horizontal stretch coefficient and the vertical stretch coefficient to acquire a target image; and controlling display of the plurality of display units of the spliced panel according to the target image.