Polymeric　carbon　nitride　(PCN)　is　an　emerging　class　of　polymer　semiconductor　photocatalysts,　but　bulk　PCN　typically　suffers　from　low　visible-light-harvesting　ability,　high　activation　energy,　and　rapid　charge　recombina-tion.　In　this　context,　using　the　same　core　building　block,　a　donor-acceptor　(D-A)　type　heptazine-based　polymer,　namely　BPCN,　was　proposed　via　Friedel-Crafts　arylation　reaction　to　tackle　these　issues.　Comparatively,　the　affording　BPCN　features　extended　light　absorption,　reduced　activation　energy,　and　suppressed　charge　recom-bination,　triggered　by　the　electron　push-pull　interactions　as　a　consequence　of　the　D-A　configuration.　BPCN　is　elucidated　to　be　an　effective　heterogeneous　photocatalyst　for　aerobic　organic　transformations　and　a　wide　range　of　substrate　scopes　and　reactions　were　realized.　Besides,　BPCN　also　showed　an　advantage　in　mediating　the　photocatalytic　water　oxidation　reaction,　achieving　a　nearly　10-fold　oxygen　evolution　reaction　(OER)　rate　over　PCN.　These　findings　demonstrate　the　great　potential　of　the　rational　design　of　heptazine-based　polymers　with　D-A　configurations　for　artificial　photosynthesis.