Addition of very small amount of Ru, Pt and Pd exhibited great effect on the Co-based catalysts prepared by mixing impregnation of cobalt (II) nitrate and cobalt (II) acetate. Added small amount of Ru to this kind of catalyst showed extremely high activity, while no apparent CH4 selectivity change was observed. However, added Pt and Pd hardly exerted effect on the activity of Co-based catalyst, but increased CH4 selectivity remarkably.