The present invention relates to a long distance imaging head-up display device, which includes an imaging projection module, a reflective diffuser and a concave mirror module, wherein a reflective diffuser is used with a concave mirror module to increase a reflective distance, to thereby obtain a longer optical path distance, so as to project image to a far distance under the same magnification of concave mirror, to reduce visual vertigo and obtain the best visual effects for drivers, to thereby improve driving safety.