NOVELTY - Catalyst comprises (wt.%) carrier i.e. gamma -alumina (Al2O3) (60-80); active ingredients i.e. nickel and iron based on nickel oxide (NiO) (10-20) and iron oxide (Fe2O3) (5-15); and auxiliary ingredients i.e. magnesium oxide (MgO) (1-10) and lanthanum oxide (La2O3) or cerium oxide (CeO2) (1-10).    USE - Catalyst used for complete methanation, preferably hydrogenation methanation of CO2 (claimed).    ADVANTAGE - The catalyst has CO2 conversion ratio and CH4 selectivity of approximately 100% under a pressure 3.0-5.0 MPa, gas hourly space velocity of 5000-10000/hour, and H2/CO2 of 4.1. It has high strength, good heat stability, anti-carbon property, and easy fluidization.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) preparation of catalyst comprising drying, roasting, and reducing by sequence immersion method, and specifically comprising (A) weighing gamma -Al2O3 carrier and keeping the temperature at 550 degrees C for 5 hours; (B) introducing auxiliary ingredients by immersion method; weighing the auxiliary ingredient in the form of nitrate; making into solution; and carrying the auxiliary ingredient on the carrier by an isopyknic immersion method, where immersion temperature is 50-80 degrees C and immersion time is 5 hours; (C) drying the product at 100-120 degrees C for 5-10 hours; (D) heating the product in a muffle furnace at 550 degrees C for 5 hours at heating rate of 2 degrees C/minute; (E) introducing the active ingredient by immersion method comprising weighing the active ingredient in the form of nitrate; making into solution; and carrying the active ingredient on the carrier containing the auxiliary ingredient by an isopyknic immersion method, where immersion temperature is 50-80 degrees C and immersion time is 5 hours; (F) heating the product in the muffle furnace at 550 degrees C for 5 hours, at heating rate of 2 degrees C/minute; and (G) finally obtaining the catalyst; and    (2) method of using catalyst comprising catalyzing carbon dioxide (CO2) hydrogenation methanation reaction under a pressure of 2.0-5.0 MPa, temperature of 300-550 degrees C, gas hourly space velocity of 5000-12000/hour, and mol ratio of hydrogen (H2)/CO2 of 4.0-4.1.