With long-chain alkylbenzene sulfonic acid as a main raw material,super overbased synthetic calcium sulfonate is produced by neutralization and super high alkalization reaction. The product has excellent alkaline storage property,good oil solubility and strong acid neutralization capability,and it can immediately neutralize organic acid and inorganic acid in oil; meanwhile it also has excellent high-temperature detergency and thermal stability. It is a preferred additive for blending over-based marine cylinder oil.