A device and a method of optimizing brightness of a liquid crystal display panel includes a plate to mount a target liquid crystal display panel, a back light to provide light to the liquid crystal display panel, a connecting unit to connect to a pad unit of the liquid crystal display panel, a detecting unit to produce a brightness signal by detecting a brightness of a predetermined region of the liquid crystal display panel, a converting unit to convert the brightness signal into a brightness data, a comparative unit to store a standard data and to compare the brightness data with the standard data, and a processing unit to produce an operation voltage according to a result signal provided by the comparative unit and to provide the operation voltage to the connecting unit, wherein the detecting unit detects the brightness by concentrating light of sight angle range is ±10° or below.