A head mounted display includes a first and second light sources, a light turning prism, a field lens group, an image output module, a first and second eyepiece modules. The first and second light sources are respectively configured to emit first and second lights. The image output module is configured to receive the first light and the second light, and to respectively generate a first image light and a second image light with corresponding image information. The light turning prism is optically coupled between the first light source (or the second light source) and the field lens group. The light turning prism is configured to vary a propagating direction of the first light (or the second light) from the first light source (or the second light source) to the image output module. The first/second eyepiece modules are configured to make the second/first image light image to first/second target positions.