Stereoscopic image displaying method and stereoscopic display device

A stereoscopic image displaying method includes providing a display panel for displaying an image, the display panel having a pixel pitch, providing a parallax barrier having a first barrier region to an Nth barrier region and a first distance between the parallax barrier and the display panel, the first barrier region to the Nth barrier region respectively having a first barrier pitch to a Nth barrier pitch, providing a second distance between the display panel and a user, and selecting a proper barrier region from the first barrier region to the Nth barrier region of the parallax barrier or adjusting the first distance according to the second distance.