Designing efficient photocatalysts for water splitting hydrogen evolution with low cost is a hot topic. In the present work, a α-Fe2O3/g-C3N4 photocatalyst with core-shell structure is successfully synthesized by an modified thermal etching method. Due to the synergy of Z-scheme and electron tunneling, the α-Fe2O3/g-C3N4 photocatalyst exhibits efficient water splitting propertiy under visible light, even red-light irradiation (about 700 nm). In-situ generated α-Fe2O3 nanoparticles facilitate the formation of 2D g-C3N4. The prepared α-Fe2O3/g-C3N4 photocatalyst shows an efficient photocatalytic activity between 500 nm and 700 nm due to the electron tunneling effect. The highest hydrogen evolution rate of α-Fe2O3/g-C3N4 photolyst is 5 mmol g−1 h−1 at λ > 420 nm. The present research provides the guidance for designing red-light-responsive photocatalysts for solar applications