NOVELTY - Carbon dioxide methanation catalyst comprises 0.1-10 wt.% active component, 1-15 wt.% auxiliary agent and carrier (remaining amount). The active component is noble metal ruthenium or rhodium. The auxiliary agent is at least one element of period table I main group, II main group or II, III and VII subgroups. The carrier is silicon dioxide, titanium dioxide, aluminum oxide, cerium oxide, zirconium dioxide and/or tin dioxide.    USE - The carbon dioxide methanation catalyst is useful in space station (claimed).    ADVANTAGE - The catalyst: has high activity and selectivity, and window width temperature and pressure operation property; and realizes circulation of oxygen supply and is energy saving.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) preparing the carbon dioxide methanation catalyst, comprising (i) dissolving specific amount of cerium and zirconium in deionized water to obtain 0.1M solution, weighing urea according to 10-12 times of molar ratio of cerium and zirconium and dissolving in deionized water, mixing the two solutions, stirring, heating at 90-110 degrees C and refluxing for 2-4 hours in an oil bath, washing and filtering, drying for overnight at 100-120 degrees C, calcining at 400-600 degrees C for 2-6 hours, and grinding completely to obtain carrier, (ii) soaking specific amount of active component in aqueous precursor solution for 1-12 hours, or precipitating using sodium carbonate or urea and depositing on the carrier, or coating carrier, auxiliary agent and active component on catalyst structure carrier and metal honeycomb to obtain semi-finished catalyst product, (iii) drying the semi-finished catalyst product at 120 degrees C for 12-24 hours and calcining at 450-550 degrees C for 2-4 hours, and (iv) reducing under hydrogen steam at 300-700 degrees C for 4-10 hours, or reducing using 2% hydrazine hydrate solution at room temperature for 12-24 hours, water washing for 5-10 times, and drying for 12-24 hours at 120 degrees C; and    (2) use method of the carbon dioxide methanation catalyst, comprising performing hydrogenation and methanation of carbon dioxide using the catalyst, and purifying ammonia synthesis gas and fuel cell gas.