The present invention provides a backlight system, which includes a light source; and a back frame, which includes at least two primary assembling pieces, the at least two primary assembling pieces being joined to form a main frame structure of the back frame; wherein the light source is carried by a first side of at least one of the primary assembling pieces, the backlight system further comprising heat dissipation elements, the heat dissipation elements having a distribution that is denser at locations closer to a center of the primary assembling piece that carries the light source in a lengthwise direction of the primary assembling piece that carries the light source. The backlight system of the present invention forms a back frame through joining so as to make the structure of the back frame simple and reduces the manufacturing cost of the backlight system, and further, through an arrangement that heat dissipation elements are arranged more densely on the primary assembling piece that carries a light source at locations closer to a center thereof in the lengthwise direction, the heat dissipation efficiency and heat dissipation performance of the backlight system are improved.