We designed a composite carrier containing oxygen vacancy defects for anchoring Pt single-atom electrocatalyst Pt SA/TiO2(OV)-CNT. The TiO2-CNT composite carrier was synthesized by solgel method, a large number of oxygen vacancy defects were introduced on its surface by high temperature heat treatment, and finally Pt SA was loaded on TiO2(OV)-CNT by the deposition-precipitation method. The structure and microscopic morphology of the composites were characterized by XRD, EPR, HAADF-STEM and XPS. The results showed that oxygen vacancy defects were successfully introduced on TiO2-CNT and Pt SA existed in the TiO2(OV)-CNT lattice, with charge transfer between the two to form Strong metal-support interactions (SMSI). Further oxygen reduction results showed that Pt SA/TiO2(OV)-CNT had a half-wave potential of 0.804 V, a mass activity MA of 451.24 mg/mgPt, and a Tafel slope of 63.75 mV/dec. The ICP results show that the Pt loading is only 1.13 % of the mass of Pt SA/TiO2(OV)-CNT, which indicated that Pt SA /TiO2(OV)-CNT catalyst can still exhibit excellent catalytic activity with low Pt loading and high atom utilization compared with commercial Pt/C catalysts. Key words: oxygen reduction; composite carrier; single atom; half-wave potential; mass activity; atomic