The invention discloses a method for improving the luminance uniformity of a backlight module. According to the method, the luminance of each independent area in a standard light guide plate is detected through cooperation of the standard light guide plate and a backlight source to be assembled, and on this basis, the lattice point distribution graph of a light guide plate to be assembled is designed, so that the light guide plate to be assembled is manufactured according to the lattice point distribution graph and replaces the standard light guide plate; in this way, luminance of the backlight module is uniform, production technology is simple, and uniform luminance of the backlight module is achieved at low cost; problems caused by non-uniform luminance of an existing backlight source are solved by adjusting the lattice point structure of the light guide plate to be assembled, and luminance uniformity of the backlight module is high; furthermore, the light guide plate to be assembled is divided into multiple independent areas through air isolation walls, luminance partitioning and independent control of regional luminance of the light guide plate are achieved, optical isolation effect is high, yield is high, quantized production can be achieved, and cost is low.