This invention provides a method for manufacturing a packaged display device, which comprises following steps of: providing a barrier plate by forming a polyimide barrier unit surrounded and defined a space on first substrate through a solidification process of a composition for barrier, wherein said solidification process being selected from the group consisting of screen printing process and lithography process; disposing a display element on second substrate; forming a covered layer by covering said second substrate and said display element with a material for packaging; disposing said barrier plate on said covered layer, thereby positioning said display element in said space of said barrier plate; proceeding a solidification treatment of said covered layer to form a packaged layer. Said composition for barrier plate comprises a main component selected from the group consisting of polyamic acid having a structure represented by formula (1), soluble polyimide represented by formula (4) and a polyimide precursor containing polyamic acid represented by formula (2) and diacid represented by formula (3). The definition of the formulas (1), (2), (3) and (4) is defined as set forth in the specification and claims.