The present invention provides a back frame of flat panel display device. The back frame includes at least two primary assembling pieces and the at least two primary assembling pieces are connected through joining; the at least two primary assembling pieces includes one primary assembling piece that carries a light source thereon and the primary assembling piece that carries the light source is provided with a heat dissipation fin assembly. The present invention also provides a method for manufacturing a back frame of flat panel display device and a backlight system. Through above arrangement, the back frame mold is made simple in structure and can reduce the expenditure of the back frame mold, and can also save the material used for back frame so as to lower down the cost of flat panel display device, and at the same time facilitates heat dissipation from a light source.