A control device and a method for image display are provided. The control device includes a mirror display unit, a backward camera unit, a reference data detection module, and an image processing module. The mirror display unit includes a mirror and a display module. The mirror generates a first image via reflection. The display module has a display surface at least partially overlapping with the mirror. The backward camera unit captures a second image, and the area of the first image is within the area of the second image. The reference data detection module generates reference data. The image processing module determines an area correspondence between the first image and the second image according to the reference data, and generates a display image from the second image based on the area correspondence. The display module displays the display image when receiving a switch command.