Digital holographic display with a two-dimensional (2D) and three-dimensional (3D) convertible feature is proposed. The 2D and 3D convertible feature is implemented by a high speed switchable diffuser. In a 3D display mode, 3D images are displayed by the principle of the digital holography with a coherent surface light source. An electrically controlled switchable diffuser changes the coherent light into a scattered surface light to display 2D images in a 2D display mode. The displayed image on a spatial light modulator for 2D and 3D display modes is in synchronizes with the status of the diffuser, diffuse or clear, which is electrically controlled by a personal computer. The experimental results show that the proposed method is capable of displaying 2D images and 3D digital hologram convertibly.