A stereo image displaying method adapted to a polarizing panel is provided. The stereo image displaying method includes the following steps. An original first eye image and the original second eye image are received. Each of the odd pixel data rows of the original first eye image is interpolation operated with at least one of two adjacent even pixel data rows of original the first eye image to serve as one of a plurality of pixel data rows of a first eye image of a display frame. Each of the even pixel data rows of the original second eye image is interpolation operated with at least one of two adjacent odd pixel data rows of the original second eye image to serve as one of a plurality of pixel data rows of a second eye image of the display frame. The display frame is applied on the polarizing panel.