A head mounted display comprises a light sensor, a first light source, a second light source, a transflective mirror, a lens, a display and a filter. The first light source is used for generating a first light beam. The second light source is used for generating a second light beam. The transflective mirror is provided on the light paths of the first light beam and the second light beam. The first light source is provided at the periphery of the lens or the light sensor. The first light beam is reflected by a first object, and enters the light sensor via the lens and the transflective mirror in sequence. The second light source is provided at the periphery of the filter. After leaving the second light source, the second light beam is reflected by a second object outside the head mounted display first, and then enters the light sensor via the filter and the transflective mirror in sequence. A using method of the head mounted display is also provided.