In-vehicle heads-up display systems allow drivers to see key data without turning their heads or looking down by virtually superimposing all types of driving information on the real-world view of the road. Head-up display systems require at least two or more virtual image depth planes to realize the augmented reality display effect truly. Currently, a variety of methods have been proposed for realizing AR-HUD systems with multiple depth planes. However, most of these designs suffer from the problem of insufficient depth of far-optical road imaging distance adjustment, which is unable to effectively respond to the visual convergence adjustment conflicts brought about by changes in vehicle speeds, affecting the driving experience and safety. Research has shown that holographic imaging technology can provide a realistic three-dimensional display effect and all the depth cues required by the human eye. At the same time, the holographic three-dimensional imaging content displayed by the use of spatial light modulator (SLM) depth of the virtual image continuously adjustable, a complete solution to the imaging of the convergence of the adjustment of conflicts, vertigo, to achieve an indeed augmented reality display effect.Based on the holographic imaging principle, the impulse response function of the holographic display equipped with a spatial light modulator and the modulation transfer function are derived, and a dual-optical path AR-HUD system that can realize continuous depth adjustment is established (Fig.4). The optical system structure was constructed by acquiring windshield surface data and extracting the application area through Zemax (Tab.1). The dual-optical path AR-HUD system was designed with an off-axis reflective optical design to solve the superposition problem of the near-optical path and far-optical path information. The system optimizes the dot column plots, MTF curves, grid and dynamic aberrations of the near- and far-optical paths. It gives the projection distance and image width variation diagrams of the projection unit of the far-optical path (Fig.10).At the end of the design optimization of the dual optical path AR-HUD system, the maximum value of the RMS radius is 10.933 µm at 15 m. The RMS radius is 23.304 µm at 3 m (Fig.6), the MTF curves, the MTFs are all greater than 0.5 at a cut-off frequency of 6 lp/mm (Fig.7). The maximum mesh aberration is less than 2% for the projected distance of 15 m. The maximum mesh aberration is less than 3% for the projected distance of 3 m (Fig.8). In the process of continuous adjustment of projection distance, the worst image quality is at the projection distance of 7 m (Fig.9), at this time, the RMS spot radius is within the radius of the Airy spot, the MTF can satisfy the requirement of more than 0.5 at 6 lp/mm, and the mesh aberration is less than 2%, which meets the acceptable range of the human eye. It can satisfy the driving demand in the actual use of the system.Aiming at the problems of the traditional AR-HU, such as the inability of the final imaging to match the depth distance of the natural scene and the poor imaging quality caused by the windshield irregularities in the holographic HUD, the theoretical feasibility of the continuous depth adjustment system is verified through the research based on the holographic imaging theory. A dual-optical path AR-HUD system with continuous depth adjustment is designed. The aberration correction capability of free-form optics is utilised to accurately correct the irregular aberration introduced by the windshield, which significantly improves the imaging quality and ultimately obtains dual-optical path AR-HUDs with imaging distances of 3 m, 7-15 m, and field of view angles of 6°×1° and 12°×4° with good imaging quality, respectively. At the same time, the dynamic aberration analysis of the designed dual-optical path AR-HUD system is carried out, which proves the stability of the designed AR-HUD system.