Magneli phase titanium sub-oxide conductive ceramic TinO2n-1 was used as the support for Pt due to its excellent resistance to electrochemical oxidation, and Pt/TinO2n-1 composites were prepared by the impregnation-reduction method. The electrochemical stability of TinO2n-1 was investigated and the results show almost no change in the redox region after oxidation for 20 h at 1.2 V (vs NHE) in 0.5 mol/L H2SO4 aqueous solution. The catalytic activity and stability of the Pt/TinO2n-1 toward the oxygen reduction reaction (ORR) in 0.5 mol/L H2SO4 solution were investigated through the accelerated aging tests (AAT), and the morphology of the catalysts before and after the AAT was observed by transmission electron microscopy. At the potential of 0.55 V (vs SCE), the specific kinetic current density of the ORR on the Pt/TinO2n-1 is about 1.5 times that of the Pt/C. The LSV curves for the Pt/C shift negatively obviously with the half-wave potential shifting about 0.02 V after 8000 cycles AAT, while no obvious change takes place for the LSV curves for the Pt/TinO2n-1. The Pt particles supported on the carbon aggregate obviously, while the morphology of the Pt supported on TinO2n-1 remains almost unchanged, which contributes to the electrochemical surface area loss of Pt/C being about 2 times that of the Pt/TinO2n-1. The superior catalytic stability of Pt/TinO2n-1 toward the ORR could be attributed to the excellent stability of the TinO2n-1 and the electronic interaction between the metals and the support.