The invention provides a display panel, a display device and a control method thereof, and belongs to the technical field of display. The display panel comprises a first base plate, a liquid crystal layer, a filling layer, a pixel electrode layer, an insulation layer and a public electrode layer, wherein each pixel electrode comprises a plurality of strip-shaped electrode units in array distribution; when no electric field is exerted to the liquid crystal layer, incident light can form total reflection in optical waveguide consisting of the first base plate, the liquid crystal layer and the filling layer, and a first state is displayed; and when an electric field is exerted to the liquid crystal layer, the liquid crystal layer can form a liquid crystal grating, and a second state is displayed. The display panel has the advantages that the contrast ratio and the luminous efficiency are high; a preparation process is simple; mass production is easy; and transparent display can be realized.