Abstract: Ultrafine Mo-Co-K catalysts were characterized by BET,XPS and TPD techniques in this paper. By comparing the characterization results with the catalytic performance for higher alcohol synthesis of the catalysts,the role of Co in ultrafine Mo-Co-K catalysts for the synthesis of higher alcohols was studied. The addition of Co into ultrafine Mo-K catalyst enhanced the activity and selectivity to higher alcohols of the catalyst, on the other hand,the addition of Co enhanced the specific surface area of the catalyst and promoted the formation of smaller pores. The catalytic performance of the catalysts correlated with their texture very well, and the above two tendency showed an excellent corresponding relationship. The electron binding energy of lower valence Mo species which might act as the active sites of higher alcohol synthesis was affected by Co less obviously. The addition of Co into ultrafine Mo-K catalyst diminished the adsorption strength of H2 and CO on the strong adsorption sites of the catalyst,which might improve the reaction of higher alcohol synthesis. The results showed that Co acted only as a structure promoter in the catalysts and affected the catalytic performance by changing the texture and strong adsorption centers for H2 and CO of the catalysts.