A back frame (23) for a flat-panel display device (20). The back frame (23) comprises main assembly components (231, 232, 233, 234, 261, 262, 281, 282, 283), secondary assembly components (235, 236), as well as support brackets (2371, 2372, 2373, 2374, 2375, 2376, 2377, 60) for fixing in place a circuit board (80). The main assembly components (231, 232, 233, 234, 261, 262, 281, 282, 283) are at least two in number, one end of at least one of the main assembly components (231, 232, 233, 234, 261, 262, 281, 282, 283) is provided with assembly parts (2311, 2312, 2361, 2362), and the secondary assembly parts (235, 236) assemble onto the main assembly parts (231,232,233,234,261,262,281,282,283). At least two main assembly components (231, 232, 233, 234, 261, 262, 281, 282, 283) assemble together by means of the corresponding assembly parts (2311, 2312, 2361, 2362); the assembly parts (2311, 2312, 2361, 2362) of at least one of the main assembly components (231, 232, 233, 234, 261, 262, 281, 282, 283) are provided with a reinforcing structure. The support brackets (2371, 2372, 2373, 2374, 2375, 2376, 2377, 60) comprise a support bracket main body (61), a first hanging part (62), a first off-set part (63) and a first flexible flip part (64). Also provided is a backlight system (21). The structural simplicity of the back frame (23) reduces the cost of the mold for the back frame and economizes on materials for the back frame (23), thus reducing the cost of the flat-panel display device (20).