An exemplary backlight module includes a light guide plate (210), a light source (211), and a retardation layer (214). The light guide plate includes a light incident surface (2120) and a light emitting surface (2121) adjacent to the light incident surface. The light source is configured to emit polarized light with a first polarization orientation, and is located at a side of the light incident surface. The retardation layer is disposed at a side of the light emitting surface, and is configured to rotate the first polarization orientation of the polarized light to a second polarization orientation.