A three-dimensional image apparatus and an operation method thereof are provided. The three-dimensional image apparatus includes a projection unit, a photographic apparatus, a display module and a control unit. In a scan mode, the control unit controls the projection unit to project a structure-light pattern onto an object to be captured in different angles relatively to the object and controls the photographic apparatus to capture a plurality of composition images corresponding to different angles of the object. The composition images are converted into a three-dimensional image in a three dimensional image format through an image conversion module, and the three-dimensional-format image may display a displaying image of the object in a specific viewing angle through the display module. The projection unit and the photographic apparatus are located at a same side of the three-dimensional image apparatus.