Covalent　triazine　frameworks　(CTFs)　represent　promising　polymeric　photocatalysts　for　photocatalytic　hydrogen　production　with　visible　light.　However,　the　separation　and　transfer　of　charges　in　CTFs　are　isotropic　because　of　the　uniform　distribution　of　donor–acceptor　motifs　in　the　skeleton.　Herein,　to　achieve　the　anisotropic　charge　carrier　separation　and　migration,　thiophene　(Th)　or　benzothiadiazole　(BT)　unit　is　selected　as　the　dopant　to　modify　the　molecular　structure　of　CTF-based　photocatalysts.　Both　theoretical　and　experimental　studies　reveal　that　the　incorporation　of　Th　or　BT　units　induces　the　anisotropic　charge　carrier　separation　and　migration　at　the　interface　of　CTFs.　The　optimized　polymer　manifests　a　much　enhanced　photocatalytic　activity　for　photocatalytic　hydrogen　production　with　visible　light,　and　thus　this　study　provides　a　useful　tool　to　design　conjugated　polymer　photocatalysts　at　the　molecular　level　for　solar　energy　conversion.　©　2022　Wiley-VCH　GmbH.