Overbased calcium sulfonate is the important raw material for formation of complex calcium sulfonate grease（CCSG）,its inherent quality is one of the most important influence factors of properties of CCSG.In order to select appropriate overbased calcium sulfonate,the phase transformation time from amorphous calcium carbonate to calcite calcium carbonate and thickening ability of different overbased calcium sulfonates,as well as the drop point,cone penetration,oil separation and rolling stability of the prepared greases prepared by different overbased calcium sulfonates were investigated.The CCSG prepared by the selected overbased calcium sulfonate shows excellent high temperature characteristics,good colloid stability and mechanical stability.It lays a foundation for the development and industrial production of high quality CCSG.