A novel crosslinked copolymer, poly (1,4,8,11-cyclotetradecane [2,2-bipyridine]-5,5-dicarboxamine) (PNH), was synthesized in high yield via a simple condensed polymerization at 45 °C. PNH exhibited a strong affinity with Fe 3+ ions in water, and the absorbance capacity of Fe 3+ in water reaches 350 mg g −1 PNH. The obtained polymeric metal complex, PNH-Fe, can be converted into PNH-covered Fe 2 O 3 nanoparticles by moderate hydrothermal treatment. Fe 2 O 3 @PNH becomes an excellent photocatalyst for the removal of water-soluble organic pollutants. Even if Fe 2 O 3 @PNH is at low catalyst loadings (0.1 g/L), it still has an excellent performance because of enhanced charge separation through the interaction between PNH and Fe 2 O 3 . Fe 2 O 3 @PNH exhibits better catalytic performance (∼90% for tetracycline (TC), 50 ppm) than pure Fe 2 O 3 (up to 3 times). This work not only broadens the synthetic utility of Fe 2 O 3 but also shows promising potential of Fe 2 O 3 for use in the treatment of water pollution.