Holographic display technology is considered as one of the most promising display technologies. However, the existing spatial light modulators (SLM) are insufficient for large-scale holographic display. In this research, a large-scale holographic 3D display system, which consists of a laser, a beam expander, three lenses, a beam splitter, two SLMs, and an aperture stop is proposed. First, a large-scale hologram is generated using the error diffusion method. Then, the large-scale hologram is divided into two holograms with the same resolution, and loaded onto two SLMs, respectively. Finally, the diffraction light fields of the two SLMs are seamlessly spliced together in space to realize large-scale holographic 3D display. The experimental results verify the effectiveness of the system.