Abstract: To address the rapid charge carrier recombination in organic semiconductors, a donor-acceptor (D-A) type covalent organic framework (COF) photocatalyst was developed through a rational molecular design and post-synthetic modification strategy. Specifically, the precursor TPT-TFT-COF was first synthesized, followed by the precise incorporation of a strong electron-donating unit, benzodithianthrene (BDTT), via a highly efficient aromatic nucleophilic substitution reaction with a conversion efficiency exceeding 90%. The introduction of BDTT units induced a robust push-pull electronic effect, significantly narrowing the optical bandgap and broadening the light absorption range. Photoelectrochemical tests confirmed that the D-A configuration effectively promoted spatial charge separation and reduced interfacial charge transfer resistance. Photocatalytic evaluations demonstrated that the resulting TPT-BDTT-COF exhibited exceptional activity for dehalogenation reactions under visible light, achieving high conversion efficiency (>99%) and yields (>90%), as well as excellent cyclic stability. This study provides a novel paradigm for precisely regulating the microenvironment of COF and developing high-performance polymer photocatalysts.