The invention relates to a composite calcium sulfonate grease and a preparation method thereof. The composite calcium sulfonate grease comprises: (A) base oil which accounts for 50-80 percent of the total weight of the grease; (B) calcium alkylbenzenesulfonate with a super high base number accounting for 10-30 percent of the total weight of the grease; (C) a composite thickener consisting of hydroxy fatty acid of C12-C22 accounting for 0.5-5 percent of the total weight of the grease, boric acid accounting for 0.5-3 percent of the total weight of the grease, and calcium hydroxide accounting for 0.5-2 percent of the total weight of the grease; (D) a disperser or similar matter accounting for 0.5-4 percent of the total weight of the grease; and (E) a transforming agent. The composite calcium sulfonate grease is prepared through the processes of mixing, stirring, heating up, homogenizing, degassing, etc. The grease not only has the advantages of high drop point, good thermal stability at a high temperature, good water resistance, good corrosion protection, excellent extreme pressure anti-wear properties, etc., but also is characterized by high drop point, good rust and corrosion resistance without additives, extreme pressure anti-wear properties, good mechanical stability, colloid stability, and nonhardening property for a long-period storage.