A system and a method for compensating uniformity of brightness are provided. The system includes an edge-type backlight assembly, a display panel, a brightness sensor, a compensating calculator, and a local dimming controller. The display panel is disposed above the edge-type backlight assembly. The display panel includes plural regions for local dimming. The brightness sensor is configured to measure whether the brightness distribution of the display panel is uniform. When the brightness distribution of the display panel is not uniform, the compensating calculator calculates a brightness compensation value corresponding to each of the regions of the display panel. The local dimming controller is configured to drive the edge-type backlight assembly according to the brightness compensation value corresponding to each of the regions of the display panel.