A head mounted display apparatus and an eye-tracking apparatus thereof are provided. The eye-tracking apparatus includes a first wave guide apparatus, a voltage control beam splitter, a first beam splitter, and an image capture apparatus. The voltage control beam splitter provides a first light path between the image capture apparatus, the voltage control beam splitter, and a target zone according to a control signal during a first time period. The voltage control beam splitter provides a second light path between the image capture apparatus, the first wave guide apparatus, the first beam splitter, and the target zone according to the control signal during a second time period. The image capture apparatus respectively captures a first image and a second image of the target zone through the first light path and the second light path.
