The invention provides a deoxidation catalyst for olefin gas, a preparation method and an application thereof. The deoxidation catalyst for the olefin gas comprises, by oxide, 0.01-5 % by weight percent of active components selected from one or more of Pd, Pt and/or Ag, 1-20 % by weight percent of an active additive selected from any one of Mn, Fe, Co, Cu and Zn compounds, and the balance being a carrier, wherein the carrier is a nano TiO2/Al2O3 composite carrier, and is prepared by a dry-mixing method, a sol-gel method or a co-precipitation method. The deoxidation catalyst is relatively high in mechanical strength, not easy to be pulverized, high in low-temperature activity, and long in service life, can be directly used for deoxidation and purification of industrial polyolefin, is free of reduction and activation, and can prevent olefin addition during a using process and can deoxidize oxygen not higher than 10000 ppm in the olefin to be less than 0.05 ppm.