A method of dynamically displaying a three-dimensional image object in a volumetric display apparatus is provided. The method includes rotating a display plate about an axis to display a volumetric three-dimensional image; displaying a first three-dimensional image of a first three-dimensional image object according to first coordinates in a first image coordinate system in the volumetric display region; sensing a position or a movement of an external real-world object within a sensing zone; and displaying a second three-dimensional image of a second three-dimensional image object according to second coordinates in a second image coordinate system in the volumetric display region. The second three-dimensional image object is obtained by reorienting the first three-dimensional image object from an initial orientation to a target orientation; and the reorientation is correlated with a position or the movement of the external real-world object.