The present invention provides a composite calcium sulfonate-based octaurea lubricating grease, and a preparation method thereof. According to the lubricating grease, the lubricating grease comprises the following components by adopting the weight of the lubricating grease as the reference, wherein the components comprise, by weight, 1) 10-70% of non-Newtonian calcium sulfonate, 2) 1-10% of higher fatty acid calcium, 3) 1-15% of small-molecule inorganic calcium or organic calcium, 4) 0.5-30% of octaurea, and 5) 10-80% of lubricating base oil. According to the present invention, the lubricating grease adopts the calcium petroleum sulfonate or the synthetic calcium sulfonate as the raw material, and contains the composite calcium thickener and the octaurea compound; the lubricating grease has properties of excellent extreme pressure antiwear property, ultralong lubricating life, excellent adhesion, water resistance, colloidal stability, high drop point, thermal stability, corrosion resistance, salt mist resistance and the like.