Covalent organic frameworks (COFs) are highly porous, crystalline organic polymers with excellent physicochemical properties, making them promising materials for advanced separation membranes. Recent advances in COF membrane fabrication have enabled the development of thin-film, composite, and mixed matrix membranes with high rejection rates (over 80%) for organic dyes and foulants. COF-based membranes, especially those embedded in polyamide thin-film nanocomposites, have shown effectiveness in desalination. However, the ordered structure and separation mechanisms of COFs remain unclear. This perspective critically evaluates the design and performance of COF membranes in water treatment, highlighting technological challenges in fabrication, functionalization, and treatment efficacy. COF membranes are fabricated using methods such as interface-assisted polymerization, in situ growth, layer-by-layer stacking, and incorporation into polyamide membranes. Pore size engineering is crucial for water treatment, with COFs capable of achieving pore sizes less than 1 nm. Surface charge and hydrophilicity can be adjusted through functionalization with groups like -COOH, -NH2, and -SO3H, enhancing salt rejection and antifouling properties. However, COF membranes still face challenges in stability, particularly in aqueous environments and under chlorination, which can lead to membrane degradation. The crystallinity of COF membranes is essential for high selectivity and permeability, and can be improved through buffer layers, controlled monomer diffusion, and solid-vapor interfaces. Despite these advancements, COF membranes have not yet achieved the performance of commercial polyamide membranes in desalination due to larger pore sizes and lower permeate flux. The integration of COFs into conventional membranes, such as TFN or FO membranes, has shown promise in improving desalination performance, but the role of COFs in pore size distribution and removal mechanisms remains unclear. COF membranes have been applied in various water treatment processes, including RO, NF, and MD, with some demonstrating high rejection rates for organic dyes and salts. However, their practical application in large-scale water treatment is limited by challenges in processability, stability, and scalability. Future research should focus on optimizing COF membrane fabrication, enhancing their performance in desalination, and addressing real-world challenges in water treatment. The development of 3D COF-based membranes and the use of electrospinning and 3D printing techniques offer new opportunities for improving COF membrane performance and functionality. Overall, COF membranes hold significant potential for water treatment, but further research is needed to overcome existing challenges and realize their full capabilities.Covalent organic frameworks (COFs) are highly porous, crystalline organic polymers with excellent physicochemical properties, making them promising materials for advanced separation membranes. Recent advances in COF membrane fabrication have enabled the development of thin-film, composite, and mixed matrix membranes with high rejection rates (over 80%) for organic dyes and foulants. COF-based membranes, especially those embedded in polyamide thin-film nanocomposites, have shown effectiveness in desalination. However, the ordered structure and separation mechanisms of COFs remain unclear. This perspective critically evaluates the design and performance of COF membranes in water treatment, highlighting technological challenges in fabrication, functionalization, and treatment efficacy. COF membranes are fabricated using methods such as interface-assisted polymerization, in situ growth, layer-by-layer stacking, and incorporation into polyamide membranes. Pore size engineering is crucial for water treatment, with COFs capable of achieving pore sizes less than 1 nm. Surface charge and hydrophilicity can be adjusted through functionalization with groups like -COOH, -NH2, and -SO3H, enhancing salt rejection and antifouling properties. However, COF membranes still face challenges in stability, particularly in aqueous environments and under chlorination, which can lead to membrane degradation. The crystallinity of COF membranes is essential for high selectivity and permeability, and can be improved through buffer layers, controlled monomer diffusion, and solid-vapor interfaces. Despite these advancements, COF membranes have not yet achieved the performance of commercial polyamide membranes in desalination due to larger pore sizes and lower permeate flux. The integration of COFs into conventional membranes, such as TFN or FO membranes, has shown promise in improving desalination performance, but the role of COFs in pore size distribution and removal mechanisms remains unclear. COF membranes have been applied in various water treatment processes, including RO, NF, and MD, with some demonstrating high rejection rates for organic dyes and salts. However, their practical application in large-scale water treatment is limited by challenges in processability, stability, and scalability. Future research should focus on optimizing COF membrane fabrication, enhancing their performance in desalination, and addressing real-world challenges in water treatment. The development of 3D COF-based membranes and the use of electrospinning and 3D printing techniques offer new opportunities for improving COF membrane performance and functionality. Overall, COF membranes hold significant potential for water treatment, but further research is needed to overcome existing challenges and realize their full capabilities.