Photocatalytic　oxidative　coupling　of　amines　is　considered　a　mild,　efficient,　and　sustainable　strategy　for　the　synthesis　of　imines.　As　a　versatile　organic　semiconductor,　conjugated　microporous　polymers　(CMPs)　are　attractive　in　photocatalysis　areas　due　to　the　diversity　of　their　polymeric　monomers.　Herein,　we　report　that　in　addition　to　the　design　of　monomers,　size-confined　polymerization　is　also　a　feasible　strategy　to　modulate　the　structure　and　photocatalysis　properties　of　CMPs.　We　adopted　dibromopyrazine　as　polymeric　units　to　prepare　pyrazine-involved　hollow　spherical　CMPs　(H-PyB)　using　a　template　method　and　successfully　performed　sizeconfined　polymerization　of　hollow　samples　by　resizing　the　templates.　Interestingly,　the　small　confinement　space　induced　the　formation　of　CMPs　with　better　conjugate　extensibility,　resulting　in　enhanced　conductivity,　narrowed　bandgaps,　improved　photoelectric　performance,　etc.　As　a　result,　small-sized　H-PyB　CMPs　had　superior　activity　for　the　photocatalytic　oxidation　of　amines.　Particularly,　the　smallest　H-PyB　CMPs　that　we　designed　in　the　present　work　exhibited　excellent　performance　for　the　photocatalytic　coupling　oxidation　of　amines.　When　using　benzylamine　as　a　model　substrate,　the　yield　of　the　corresponding　imine　reached　similar　to　113　mmol　center　dot　g(-　1)center　dot　h(-1),　accompanied　by　almost　100　%　selectivity.　Furthermore,　the　as-designed　confined　samples　exhibited　stable　photocatalytic　activity　as　well　as　good　applicability　for　oxidative　coupling　of　different　amines.　This　work　not　merely　reports　a　kind　of　CMP　photocatalysts　with　excellent　performance　for　the　imine　coupling　oxidation　but　also　proposes　an　alternative　strategy　for　constructing　high-performance　organic　photocatalysts　by　size-confined　synthesis.