Embodiments of the present application disclose a method for manufacturing a naked-eye 3D device and a naked-eye 3D device. The method includes: forming a display module including a plurality of pixel islands; forming a spacer layer on the display module; and forming a micro-lens array on the spacer layer, wherein the spacer layer is formed to have a thickness such that the plurality of pixel islands are located at a focal plane of the micro-lens array. The method further includes: forming an alignment mark between the spacer layer and the display module, wherein the alignment mark is used for, when forming the micro-lens array, aligning each micro-lens in the micro-lens array with one of the plurality of pixel islands.