A diffusion plate of a backlight structure and a display device using the same are provided. The diffusion plate is used in the backlight structure having several light emitting diodes. The diffusion plate includes a main body with many depression structures positioned on a surface of the main body. The surface faces the light emitting diodes. Each depression structure is positioned above the corresponding light emitting diode and includes an inclined surface. An inclined angle is formed between each inclined surface and a central axis of the corresponding light emitting diode for refracting the light emitted by the corresponding light emitting diode.