A light adjusting sheet includes a base and a first light adjusting structure layer. The base includes a first surface and a second surface opposite to the first surface. The first light adjusting structure layer is disposed on the first surface of the base, and the first light adjusting structure layer includes a plurality of light adjusting structures. Each light adjusting structure includes a major axis, a minor axis and a thickness, wherein the major axis of the light adjusting structure is in parallel with an extending direction. A ratio of a length of the minor axis to a length of the major axis is between 0.093 and 0.6, and the thickness is between 2 μm to 6 μm. A backlight module using the light adjusting sheet can achieve high brightness and large viewing angle.