A transparent displaying base plate and a transparent displaying device. The transparent displaying base plate includes a displaying layer (2) and a liquid-crystal grating layer (3) provided on one side of the displaying layer (2), the displaying layer (2) includes black matrixes (15) and displaying regions (A) defined by the black matrixes (15), the liquid-crystal grating layer (3) is provided with a backlight unit on one side that is further away from the displaying layer (2), and the backlight unit includes a backlight layer for exiting backlight light rays to the displaying layer (2), and at least a light focusing layer for focusing the backlight light rays directly facing the positions of the displaying regions (A) to the black matrixes (15).