A display and projection device includes a first shell, a display module, a projection light valve, and a projection lens. The first shell has a display surface and a non-display surface. The display module is disposed within the first shell. The display surface of the first shell exposes the display module. The projection light valve is disposed within the first shell and capable of emitting an image light beam, and the non-display surface of the first shell exposes the projection light valve. The projection lens is disposed outside of the first shell and is located at a transmission path of the image light beam. The projection lens is detachably connected with the non-display surface of the first shell. Moreover, a projection device including a Fresnel lens is also provided.