Phenol is difficult to be naturally degraded due to its benzene ring and is also serious harmful to human health. Heterogeneous photo-Fenton is an effective method of chemical oxidation to remove phenol in wastewater with environmental friendliness and sustainability. Herein, one composite α-Fe2O3/g-C3N4 for heterogeneous photo-Fenton has been synthesized by hydrothermal first and then calcination using FeCl3•6H2O and g-C3N4 as raw materials. The catalyst shows wide visible-light responsive feature, tight heterojunction structure and superior electron transfer ability, which finally lead to significant improvement on degradation efficiency. Based hydroxyl radical of scavenger results, one type Ⅱ heterojunction was proposed to explain the transfer and migration of photoelectrons under internal electronic field. The accumulated electrons in the CB reduced ≡Fe(Ⅲ) to ≡Fe(Ⅱ) in active site of solid α-Fe2O3. This work provides a facile and new method to synthesize α-Fe2O3/g-C3N4 and as an effective heterogeneous photo-Fenton catalyst for environmental remediation.