To promote the development of iron oxide-based photocatalysts and its application in the field of water environment remediation, the key is to tackle the issues of insufficient thermodynamic reaction capacity of electrons and poor surface catalytic sites for O₂ catalytic activation due to the positive conduction band bottom position of iron oxide. In this regard, modulating the photo-generated electrons via modification on the controlled nano-sized iron oxide is an effective method for improving the photocatalytic activity of iron oxide. In this work, small sized pure α-Fe₂O₃ nanoparticles were synthesized by a urea modulate phase separation hydrolysis-solvothermal method. Based on this, the α-Fe₂O₃ nanoparticles were controllably modified by copper phthalocyanine (CuPc) through a simple wet chemical method. Results show that the as-prepared optimized sample (mass fraction of CuPc and α-Fe₂O₃ is 1%) exhibited nearly 2.5 times enhancement for photocatalytic 2,4-DCP degradation compared with the pure α-Fe₂O₃ sample. Through DRS, Raman, and FT-IR, it was revealed that CuPc and α-Fe₂O₃ had an effective interface connection by hydrogen bonding. Based on the analysis of hydroxyl radicals test and electrochemical test, the enhanced photocatalytic degradation activities could be attributed to the significantly improved photo-generated charge separation and the promoted O₂ activation. In addition, the characteristic absorption of CuPc in longer wavelengths could further extend the range of visible-light response of the nanocomposites. Significantly, this efficient strategy can also be applied to other metal phthalocyanine materials for the modification of α-Fe₂O₃.