A head-mounted display having a first light incident region and a first light emitting region is provided. The head-mounted display includes a first light-guide plate, a first micro-display, a first reflector, a first collimating lens and a first filling structure. A first inner surface of the first light-guide plate has plural first hollow microstructures located in the first light emitting region. The first micro-display is located in the first light incident region and faces the first inner surface. The first reflector is located in the first light incident region, obliquely disposed at the first light-guide plate and faces the first micro-display. The first collimating lens is disposed between the first reflector and the first micro-display. The first filling structure fills in the first hollow microstructures, wherein a refractive index of the first filling structure is greater than a refractive index of the first light-guide plate.