The invention discloses a composite calcium-sulfonate-based tetrapolyurea lubricating grease and a preparation method thereof. With the weight of the lubricating grease as a reference, the lubricating grease comprises components of: (1) 10-70% of non-Newtonian fluid calcium sulfonate; (2) 1-10% of higher fatty acid calcium; (3) 1-15% of small-molecule inorganic acid calcium or organic acid calcium; (4) 0.5-30% of tetrapolyurea; and (5) 10-80% of lubricating base oil. According to the lubricating grease, calcium petroleum sulfonate or synthesized calcium sulfonate is adopted as a raw material, and the lubricating oil contains a composite calcium thickening agent and a tetrapolyurea compound. The lubricating grease has excellent extreme pressure wear resistance, ultra-long lubricating life, good adhesion, water resistance, colloid stability, high dropping point, thermal stability, corrosion resistance, and salt spray resistance.