A new monoclinic-rich CsPbBr₃/porous α-Fe₂O₃ with 3D/3D heterojunction has been prepared by a facile one-step ligand-assisted reprecipitation (LARP) under low temperature and air atmosphere. The morphologies (i.e., cubic and monoclinic phases) of CsPbBr₃ are easily tuned by varying the ratios of precursor solution during the LARP process. Upon the heterojunction of monoclinic-rich CsPbBr₃ with porous α-Fe₂O₃, the electron consumption rate is further enhanced to 3.38 mmol g^-1 h^-1, which is ca. 2.4-fold improvements of pristine monoclinic-rich CsPbBr₃. The surpassing performance could be attributed to the higher CO₂ uptakes, superior charge separation and H₂O photooxidation via the photoinduced holes in the valence band of α-Fe₂O₃. The XRD patterns of CsPbBr₃ (denoted as CPB-1), α-Fe₂O₃ (denoted as Fe₂O₃) and CsPbBr₃/α-Fe₂O₃ (denoted as CPB/Fe₂O₃-y) can be seen in Figure 1. The co-existence of monoclinic (JPCDs 18-0364) phases of CsPbBr₃ together with α-Fe₂O₃ (JPCDs 33-0664) implies the successful synthesis of CPB/Fe₂O₃-y. A possible charge separation and transfer mechanism of CPB/Fe₂O₃-3 composite can be proposed as shown in Figure 2. The EF of CsPbBr₃ (-5.39 eV vs. vacuum) is higher than that of α-Fe₂O₃ (-5.57 eV vs. vacuum), resulting in free electron transfer from CsPbBr₃ to α-Fe₂O₃ until the equilibrium of their EF upon the intimate contact of CsPbBr₃ and α-Fe₂O₃. As such, the creation of built-in electric field together with the band edge bending would be occurred at the interface of CPB/Fe₂O₃-3. Due to the alignment of EF and band bending at the interface of CsPbBr₃/α-Fe₂O₃, the photogenerated electrons in the CB of α-Fe₂O₃ (downward band bending) would recombine with photoinduced holes in the VB of CsPbBr₃ (upward band bending) via non-radiative recombination at the interface, forming the direct Z-scheme charge transfer pathway. Consequently, the photoexcited electrons in the CB of CsPbBr₃ possess higher potential to perform the photoreductions, including CO₂-to-CO, CO₂-to-CH₄ and H⁺-to-H₂. At the same time, the photooxidation of H2O can be occurred by the holes on the VB of α-Fe₂O₃. The Z-scheme charge transfer mechanism of CsPbBr₃/α-Fe₂O₃ composite not only exhibit the superior photoactivity in CO₂ photoreduction but also enhance the chemical stability of CsPbBr₃, which demonstrated the great potential in the photoelectric applications.