Disclosed is a backlight module. The backlight module includes a backplane. The backplane is provided with a groove therethrough. Two sides and/or two ends of an optical diaphragm of the backlight module each are connected with a bendable flap which passes through the groove and is attached to the backplane. The backlight module has a simple structure without a plastic frame or a frame sealant, and an optical diaphragm in the backlight module can be fixed. A super narrow frame of the backlight module can be realized.