A system for testing a flat panel display having a flat display panel assembly includes a testing stage for arranging the flat display panel assembly, a measuring apparatus being disposed on the testing stage and for measuring a spectrum of a transmitted light passing through a measuring region of the flat display panel assembly from a light source, a transporting apparatus for moving the measuring apparatus at a constant acceleration on the testing stage, a defect informing apparatus being electrically connected to the measuring apparatus and for informing an existence of defect, a type of defect, and a severity of defect by processing an electrical signal of the spectrum transmitted from the measuring apparatus.