An operating method of a display device includes controlling a shift of a cursor of a user interface reference frame according to a shift of the pointing device with reference to an initial point in a 3D spatial reference frame; and updating a position of the initial point in the 3D spatial reference frame according to an updating signal. An advantage of the present invention is when the operating range is changed, reference coordinates utilized by the pointing device are appropriately adjusted, so as to lower the affect of offset, allowing the pointing device to be applied in different areas/directions without having the cursor displayed on the display device to incorrectly reflect shift of the pointing device.