The performance-enhancing strategy of a single pathway for perovskite has been widely studied. In this work, the dual-pathway strategy of A-site Ce substitution and nitric acid selective dissolution was proposed. The catalytic oxidation performance of LaMnO 3 exhibits the characteristic of hierarchical regulation, that is, a steplike improvement, which avoids the limitation of performance improvement of the single pathway. The B-site Mn with catalytic activity was in situ reconstituted on the surface to build a Mn-rich surface. The obtained sdLa 0.7 Ce 0.3 MnO 3 has the advantages of good oxygen mobility, high Mn 4+ /Mn 3+ molar ratio, and large specific surface area, and this material showed excellent catalytic oxidation performance for organics, which can realize colorimetric chemical oxygen demand detection at room temperature. Here, Ce substitution improved the oxidation capacity by improving the oxygen mobility and the ratio of Mn 4+ /Mn 3+ , and further nitric acid treatment not only accelerated the in situ reconstruction of B-site Mn but also increased the specific surface area.