A head mounted display, which combines a Erfle eyepiece with a reflective relay system and uses a micro display of the reflective liquid crystal on silicon with the diagonal size 18mm, has been designed. The sign of the field curvature, either the sagittal or the tangential, of the relay system is on the contrary to that of the eyepiece, which makes the system possess smaller field curvature and astigmatism. The adoption of the relay lens makes the system not only suitable for the micro display with smaller size but also offering enough space for light source in the reflective micro display. The system is with smaller aberration, enough exit pupil diameter and eye relief, and reasonable size and weight in the specific application of head mounted display.