Herein, a two-dimensional/two-dimensional (2D/2D) Bi₂O₂CO₃/SrTiO₃ (BOC/STO) direct Z-schemes heterojunction photocatalysts with perfect lattice matching are successfully prepared for efficient photocatalytic CO₂ reduction. Results show that as-prepared BOC/STO composites follow the orientation relationship of (0 2 0) _BOC// (2 0 0) _STO and both two planes have a lattice spacing of 0.26 nm, resulting in the formation of perfect lattice matching between BOC and STO, which implying BOC/STO heterostructure has an ideal channel for charge transport. In addition, the DFT calculation confirms the direct Z-schemes heterojunction is formed at the BOC/STO interface, which can facilitate efficient migration and separation of photogenerated carriers. Combining the advantage of direct Z-schemes heterojunction and good lattice matching, the optimized BOC/STO catalyst performs the photocatalytic reduction of CO₂ to CO and CH₄ which are ∼ 2.61 times and ∼ 20.47 times for STO, respectively. The selectivity of 20 %-BOC/STO for CH₄ increases to 79 %. The calculations confirm the higher adsorption energy of CHOO^– and CO and the lower reaction energy of CHO^– on BOC/STO than pure BOC or STO, resulting in the higher selectivity performance of BOC/STO for CO₂ photocatalytic reduction.