A backlight module, a display device, and a method of assembling a display device are disclosed. The backlight module includes a backplate, a middle frame, and a bonding adhesive. The middle frame is disposed on the backplate. A first adhesive holding slot is disposed between the backplate and the middle frame. At least one adhesive passage hole is defined in the middle frame. One end of the at least one adhesive passage hole is connected to the first adhesive holding slot, and another end of the at least one adhesive passage hole defines an opening at a top of the middle frame.