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The balance centered at Cr3+, La3+ and Al3+ was investigated and the stabilizing mechanism of Cr3+ was proposed during crystal remolding. The crystallinity of bulk STO perovskite is improved by the molten-salt method, and the exposure of new non-equivalent facets is more conducive to internal charge separation and migration. The above development is helpful for the overall water splitting under visible light. [Display omitted] • Designed single-crystalline La/(Cr, Al) co-doped SrTiO 3 was successfully prepared. • Introduced Cr3+ for visible-light excitation is fixed and stabilized by La3+ and Al3+. • Ti3+ defect concentration is effectively suppressed after crystal remolding. • The designed SrTiO 3 material performed well in visible-light-driven water splitting. Achieving efficient solar-to-hydrogen conversion through visible-light-driven overall water splitting poses a significant challenge for particulate photocatalysts. Although bandgap engineering can be realized by ion doping, the introduced defects simultaneously enhance the recombination of electron-hole pairs. Herein, La/(Cr, Al) co-doped SrTiO 3 was remolded via the ion implantation flux method. The La, Cr and Al achieve valence state equilibrium upon stabilizing the crystal lattice, resulting in visible-light absorption. The optimized La/(Cr, Al)-SrTiO 3 photocatalyst exhibits an overall water-splitting reaction under visible light, yielding 73.2 μmol·h−1 for H 2 and 35.0 μmol·h−1 for O 2 with an apparent quantum yield of 1.44 % at 420 nm. Based on theoretical calculation, we proposed a La, Al-cooperated mechanism that a little Cr3+ was fixed by the surrounding Al3+, and the valence state was stabilized by La3+ during the crystal remolding, thereby giving the guidance for designing visible-light materials applied in overall water splitting. [ABSTRACT FROM AUTHOR]