An optical coherence tomography apparatus includes a light source, a light coupling module, and an optical path difference generating module. The light source emits a coherent light. The light coupling module divides the coherent light into a first incident light and a second incident light. The first incident light is emitted to an item to be inspected and a first reflected light is generated. The second incident light is emitted to the optical path difference generating module, a second reflected light is generated according to the second incident light by the optical path difference generating module through changing the transparent/reflection properties of at least one optical devices of the optical path difference generating module, so that there is a optical path difference between the first reflected light and the second reflected light.