A display device comprising a first substrate, a second substrate, a blue phase liquid crystal layer and an optical element is provided. The first substrate has a display area and is opposite to the second substrate. The blue phase liquid crystal layer is disposed between the first and the second substrate and reflects a light selectively. The spectrum peak of the light is within an intersection interval corresponding to a cross point of x_bar, y_bar and z_bar stimulus value spectrums, and the intersection interval has a wavelength range from 480 nm to 520 nm. The optical element has at least one function for adjusting a phase of the light or absorbing the light.