Catalytic oxidation of propane as a representative molecule of light hydrocarbons (LHs) is of special interest for energy utilization and pollution abatement but is challengeable due to its stable C-H bonds. Here, Ru supported on porous and defect-rich CeO₂ nanosheets catalysts were prepared and investigated for catalytic oxidation of propane, and the Ru/CeO₂ catalyst using chlorine-free Ru precursor (RuN/CeNS) presented an ultra-high activity with complete conversion at 150 °C. A series of well-designed experiments and characterizations illustrated that the high-density and uniform Ru-O-Ce interfaces were determinant for propane oxidation due to the possible asymmetric bridged adsorption and activation. The presence of chlorine species suppressed the dispersion of RuO_x species and the formation of Ru-O-Ce interfaces, which also accelerated the sintering of CeO₂ and Ru-O-Ce interfaces at high temperatures. This work highlighted the experimental insights into the active interfacial sites of ultra-active Ru/CeO₂ for propane oxidation. It contributed to an in-depth understanding of the activation of C-H bonds in LHs and the preparation of supported noble metal catalysts.