The invention discloses a deoxidizing catalyst for a coal-seam gas containing oxygen and a preparation method as well as an application thereof. The deoxidizing catalyst of the invention consists of an active component, an active auxiliary and a porous carrier. The active component is the compound of Co; the active auxiliary is one or more compounds of Mn, Fe, Zn and Cu; the porous carrier is one or more of aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, silicon oxide, a phosphor-aluminium molecular sieve, an A-typed molecular sieve, an X-typed molecular sieve, a Y-typed molecular sieve, a mordenite, a ZSM-5 zeolite, diatomaceous earth, kaolinite, natural clay, aluminum silicate and magnesium silicate; calculated by oxide, the weight percentage of the active component is 1 to 60 percent; the weight percentage of the active auxiliary is 1 to 50 percent; the rest is the carrier. The catalyst of the invention has certain sulfur-resistance performance, is applicable to the deoxidization treatment of coal-seam gas with an oxygen content of 3 to 6 percent (V / V) and is capable of causing the oxygen content in the coal-seam gas to be lower than 0.5 percent by deoxidization.