A transparent display system including a display panel, a data acquisition module and a computation module is provided. The data acquisition is adapted to capture a field luminance of a field where the display panel is located and a display information luminance of display information of the display panel. The computation module determines whether a luminance contrast of the display information falls within a range from a lower boundary to an upper boundary, wherein the luminance contrast of the display information equals to the field luminance plus the display information luminance and then divided by the field luminance. If it is determined that the luminance contrast of the display information does not fall within the range from the lower boundary to the upper boundary, a luminance contrast optimization procedure is performed. An operation method of the transparent display system is also provided.