The　architectural　design　and　fabrication　of　low‐cost,　high‐performance　organic　scintillators　are　critical　for　medical　imaging　and　material/device　analysis.　However,　achieving　large‐area　and　high‐transparency　organic　scintillators　in　a　low‐cost　and　easy‐to‐implement　method　remains　a　challenge.　Herein,　a　new　design　strategy　for　regulating　the　side　chain　length　of　maleimide　derivatives　is　demonstrated　to　develop　organic　scintillators　for　achieving　low‐cost,　large‐area,　and　high　spatial　resolution　in　X‐ray　imaging.　The　effective　intermolecular　interactions　and　relatively　twisted　molecular　structure　endow　PAM‐M4　molecule　with　outstanding　scintillator　properties.　More　importantly,　as　demonstrated　for　the　first　time,　pure　organic　glassy　films　with　a　diameter　over　10 cm　and　high　optical　transparency　can　be　prepared　by　the　developed　melt‐quenched　method　using　PAM‐M4　crystal　powder　as　a　raw　material.　This　glassy　film　exhibits　excellent　X‐ray　imaging　ability　with　a　spatial　resolution　as　high　as　27.0 lp mm−1　at　MTF = 0.20,　which　is　one　of　the　best　results　among　reported　organic　scintillators.　The　results　of　this　work　not　only　develop　a　new　design　strategy　for　high‐performance　organic　scintillators　but　also　demonstrate　a　reliable　approach　to　fabricating　large　area　screens　with　superior　spatial　resolution　for　medical　or　industrial　X‐ray　imaging　applications.