The invention relates to a 3D holographic digital light processing projection device, which comprises a first light source, a second light source and a computer, wherein red light emitted from the first light source is divided into coherent light and incoherent light through a beam splitter after being expanded and collimated; the coherent light stores image information in a beam into a holographic recording material thin film; the incoherent light is reflected to the holographic recording material thin film through a flat reflector as a reading beam; the beam, with the holographic image information, diffracted from the holographic recording material thin film is reflected through a projecting flat reflector and then is emitted along the horizontal direction; and purple light emitted from the second light source directly irradiates the holographic recording material thin film as an erased beam after being expanded and collimated. Compared with the prior art, the information erasing time is shortened and the information updating speed is relatively high, so that a dynamic three-dimensional holographic image which can be observed by an observer in any direction is provided.