The catalyst with strong metal-support interactions often exhibits high catalytic activity. This study aims to prepare sensitive materials with strong metal-MOS interactions and explore their sensitization mechanism. Sn-PdPt/TiO2 was obtained by in-situ decorating PdPt bimetals on the surface of TiO2 NSs using Sn2+ as the reducing agent, and PdPt/TiO2 was prepared by traditional reduction method. Compared with TiO2 sensor, PdPt/TiO2 and Sn-PdPt/TiO2 sensors exhibited higher sensitivity, selectivity, lower operating temperature (200 °C) and detection limit (ppb level) to CO and H2. The sensitization of PdPt bimetal to TiO2 should be ascribed to the high catalytic activity of PdPt bimetal towards O2, H2 and CO, Schottky barrier at the interface between TiO2 and PdPt NPs, and the multiple valence states (Pd0, Pd2+ and Pd4+) of Pd will undergo mutual transformation during gas sensing reactions. And Sn-PdPt/TiO2 sensor exhibited higher sensitivity, selectivity and better stability than those of PdPt/TiO2 sensor, which can be attributed to the introduction of SnO2 and the stronger interaction between PdPt and TiO2 due to the in-situ reduction reaction. This study can provide some reference for preparing the MOS based gas sensing materials with strong metal-support interactions and understanding the sensitization mechanism of PdPt bimetal.