The development of covalent organic frameworks (COFs) with robust linkages is fundamentally important for the photocatalytic production of H₂O₂. In this work, a series of isostructural COFs with robust imidazole linkage were synthesized as photocatalysts for H₂O₂ production via the precise N-substituted microenvironment regulation (benzene, pyridine, pyrimidine, and triazine). The corresponding frameworks enable water and dissolved oxygen to reach the catalytic sites easily via planar skeletons and regulation of nitrogen-atom numbers. Additionally, the N-adjustment of heterocycle units in these COFs could significantly regulate the electronic band structures, light-harvesting capacity, and hydrophilic properties. The experimental investigation demonstrated that the photocatalytic process of COFs was composed of a dominant and indirect two-electron (2e⁻) oxygen reduction reaction (ORR). Notably, compared to H-COF (benzene), P-COF (pyridine), and M-COF (pyrimidine), T-COF with triazine unit exhibited the highest H₂O₂ production rate of 42,180 μmol·g⁻¹·h⁻¹ due to its wider visible light absorption and higher separation efficiency of photogenerated electron-hole pairs. Theoretical investigations confirmed that N-heterocycle units in COFs could precisely modulate the energy barrier related to the formation of *OOH and *O₂. This study is expected to provide a new way for rationally designing imidazole-linked COFs as promising photocatalysts for efficiently photocatalytic H₂O₂ generation.