The present invention relates to a cathode active material for a lithium-sulfur battery and a method of preparing the same, and more particularly, to a cathode active material for a lithium-sulfur battery comprising: an amphiphilic polymer comprising hydrophilicity parts and hydrophobicity parts; and a sulfur-carbon composite, and a method of preparing the same. When a lithium-sulfur battery is prepared using the cathode active material, there is an effect which may enhance the electric conductivity in an electrode, cycle characteristics and capacity.