Previous experimental reviews have comprehensively concluded the available organic linkers, possible synthetic strategies, corresponding properties and applications of different ordered organic frameworks , providing useful references to design new structures. The first formation of porous, crystalline, COFs by Yaghi and co-workers in 2005 opened new avenues for the exploration of polymerization strategies to form crystalline 2D polymers from designed monomers at various interfaces . Onsurface synthesis represents an attractive strategy for the atomically precise 2D polymer synthesis because the surface serves as a template and catalyzes the bond formation, and offers direct imaging capabilities through scanning probe techniques, see Fig. [98-100]. The reversibility in the covalent bond formation is an essential prerequisite for constructing large-scale, high-quality 2D polymers together with a well-balanced diffusion and reactivity of the adsorbed precursor. Therefore, well-ordered 2D polymers achieved via a hot deposition approach, demonstrated for 2D HT-polymers on a metal surface . These results confirm the synthesis possibility and stability of 2D HTpolymers using surface coupling methods. In addition, the controlled synthesis of fewlayer 2D polymers was also successfully achieved at the air-liquid interface, for example polyimide crystals were synthesized on the surface of water, assisted by surfactant monolayers . In conclusion, the discussed examples indicate the high feasibility of constructing 2D conjugated polymers from appropriate organic monomers for photocatalysis.