The catalytic activity of Mo-based catalysts prepared from (NH4)6Mo7O24 and (NH4)2MoS4 was compared in the sulfur resistant methanation process. The catalyst using oxide precursor had relatively higher activity than the catalyst using sulfide precursor, and the presulfidation procedure almost had no effect on the catalytic performance of the catalyst using oxide precursor. In view of the characterization results, it could be supposed that the amorphous MoS2 was more active for sulfur-resistant methanation than the crystalline MoS2. The molybdenum sulfides and oxides with lower valence states (Mo4+, Mo5+) could be responsible for the catalytic activity and make a possible contribution to the carbon monoxide methanation in the reaction condition.