The combination of donor–acceptor (D–A) structures presents a viable strategy for fabricating covalent organic frameworks (COFs) with exceptional photocatalytic performances. Nevertheless, the selection of functional groups on donor or acceptor building blocks and their effect on the macroscopic properties of COFs are ambiguous. In this study, we tactfully synthesized a pair of Py-DBT-COFs from the same pyrene (Py) donor and 4,7-diphenylbenzo[c][1,2,5]thiadiazole (DBT) acceptor cores with distinct primitive functional groups. The primitive functional groups of building units determine the photocatalytic properties of corresponding Py-DBT-COFs. Specifically, Py-C-DBT-COF synthesized from Py-4CHO and DBT-2NH₂ showcases a splendid H₂ evolution rate as high as 21,377.7 μmol/(g·h) (with 5 wt.% Pt) originating from better charge transfer capacity, which is significantly superior to that of Py-N-DBT-COF constructed from Py-4NH₂ and DBT-2CHO. The distinct photocatalytic performances of the two COFs are demonstrated to originate from the different charge separation and transfer capabilities. This work supplies a new avenue for optimizing the photocatalytic performance of D–A COFs from the perspective of primitive functional group selections.