Mobile device has been the most important personal computational platform. Researches increasingly focus on glasses-free 3D display that features thin form factor and low power consumption. Once glasses-free 3D display is applied in the mobile devices, it will affect or even change the observation habit and thinking manner of human being. In this paper, the solutions that were compatible with flat display were introduced. Parallax barrier, lenticular lens array, spatio-temporal multiplexing 3D display, integral 3D display, compressive lightfield display, and vector 3D display were successively introduced in detail. Furthermore, the limitations that currently prevent these technologies from commercialization were discussed in depth. Finally, the potential research trends were highlighted.