An autostereoscopic display apparatus is provided and includes a first lenticular lens array, a second lenticular lens array, an optical diffuser layer, an image projector module and a switch unit. The optical diffuser layer is disposed between the first lenticular lens array and the second lenticular lens array. Multiple image beams generated by the image projector module are projected to a plurality of observing regions on an observing plane through the first lenticular lens array, the optical diffuser layer and the second lenticular lens array. The switch unit rotates the second lenticular lens array in accordance with the autostereoscopic display apparatus operates situated at a three-dimensional (3D) display mode or a two-dimensional (2D) display mode.