An optimization method and a pre-stage device for brightness compensation, includes: providing a brightness obtaining apparatus; photographing a to-be-compensated panel to obtain a brightness compensation reference frame, where the to-be-compensated panel has first pixel units, the brightness obtaining apparatus has second pixel units, the brightness compensation reference frame includes photographing units, and the photographing unit includes second pixel units, where the second pixel unit is bigger than the first pixel unit; using four second pixel units at four endpoints of each of the photographing units as brightness references, and obtaining pieces of brightness compensation data of the other second pixel units in the photographing unit by using a specific operation mode; and performing brightness compensation for the first pixel units corresponding to each of the photographing units by using the pieces of brightness compensation data.