The invention relates to superstrong extreme pressure antiwear lubricating grease and a preparation method thereof; particularly, a densifier is generated by calcium sulfonate with a high base number through a phase inversion reaction, and the lubricating grease is prepared by combining base oil with other functional additives, wherein the base oil is combined by base oil with high viscosity and medium viscosity. The method comprises the following steps: stirring and mixing the composite base oil and the calcium sulfonate in a reaction vessel, heating, adding a phase inversion promoter, glacial acetic acid, and water, heating and reacting at a constant temperature, adding calcium hydrate, aliphatic acid and boric acid after the phase inversion is completed, reacting at a constant temperature, heating and dehydrating, adding an anti-oxidant, refining, transferring the materials into a blending vessel, adding an eutectic rolling additive and an adhesion improver, dispersing and homogenizing the mixture, filtering, and degassing to obtain the finished product. The lubricating grease of the invention has excellent water sprinkling resistance, excellent high and low temperature performance, superstrong extreme pressure antiwear performance, excellent pumping performance, outstanding shearing stability, and antirust performance.