<p>Efficient detection of nitroaromatic explosives remains a great challenge, and covalent organic frameworks (COFs) incorporating aggregation-induced emission (AIE) units provide a promising platform for high-performance fluorescent sensing. Herein, we designed and synthesized both two-dimensional (2D) and three-dimensional (3D) AIE-active COFs to systematically investigate how dimensional differences (pore architecture, charge transfer efficiency, and AIE behavior) regulate sensing performance. Through a “4+4” imine condensation strategy, a 2D sql topological COF (TPPDA-TPTPE) was obtained from a planar tetraamine (TPPDA), whereas a 3D <b>pts</b> topological COF (JUC-646) was constructed from a twisted tetraamine (BMTA) with <Emphasis Type="BoldItalic">T</Emphasis>_<b>d</b> geometry—using the same TPTPE linker. Both COFs exhibit high crystallinity, stability, and strong AIE-derived luminescence, but show strikingly different sensing performances. In particular, JUC-646 achieves a quenching constant of 6.99×10⁴ L/mol toward 2,4,6-trinitrophenol (TNP), nearly five times higher than that of TPPDA-TPTPE. This superior performance originates from the 3D open-channel structure (facilitating analyte diffusion), enhanced host-guest interactions, and energetically favorable photoinduced electron transfer—all of which are derived from dimensional differences. This comparative study explicitly establishes a structure-function relationship between framework dimensionality and sensing performance, offering direct guidance for the rational design of AIE-active COFs with tailored dimensionality for efficient explosive detection.</p>