A stereoscopic display device includes a display panel, and a light modulator. The display panel provides a first display information and a second display information alternately by scanning. The light modulator is disposed on the side of a display surface of the display panel and receives the first display information and the second display information. The light modulator provides a first modulating mode and a second modulating mode alternately by scanning synchronously with the display panel. The first modulating mode corresponds to the first display information, and renders the first display information having a first polarization state; the second modulating mode corresponds to the second display information, and renders the second display information having a second polarization state.