Lenticular lens is composed of many orderly convex lens, matched with certainthickness of medium (acrylic, PS board or glass, etc.). When people watch theimage in the back of grating sheet through grating, because of the refraction principle and the light convergence of convex lens, the displacement images seen by people are segmented, but people's eyes have parallax, thus people see a fewiamges with parallax and from different angles. Human brains process and synthesize these images with displacement to form the image with a certaim depth,namely 3D image seen by human eyes.