The embodiments of the present invention disclose a vacuum cell-assembling device and a cell-assembling method. The vacuum cell-assembling device comprises: an upper substrate, a signal processing apparatus, and a lower substrate provided opposite to the upper substrate, wherein the upper substrate is provided with a light-emitting apparatus thereon, and the lower substrate is provided a photosensitive receiving element array thereon, and the photosensitive receiving element array is connected with the signal processing apparatus, and the signal processing apparatus is adapted for converting the electrical signals from the photosensitive receiving element array to a liquid crystal diffusion-simulation image.