The operation status of high temperature methanation catalyst and low temperature methanation catalyst are compared. Both of them can ensure a 100% qualification rate of methanated hydrogen product, but low temperature methanation catalyst can save 3,392 tons of super high pressure steam each year. Lower steam temperature, pressure and reaction temperature are favorable for the stable and safe operation of ethylene plant, and the 2,000～8,000 h^-1 space velocity and high temperature resistant properties of low temperature methanation catalyst contribute to greater operational flexibility.