We have studied the formulation and performance of lithium complex greases which could be used under severe lubrication conditions. Thickeners of lithium soap-lithium salt were prepared from 12-hydroxy stearic acid, boric acid, dialkyl sebacates and lithium hydroxide monohydrate. The optimum molar ratio of 12-hydroxy stearic acid and dioctyl sebacate was 15:1 and that of 12-hydroxy stearic acid and dioctyl sebacate was 15:1 and that of 12-hydroxy stearic acid and boric acid was 3:1, which was 40:60(%) weight ratio of boric acid and dioctyl sebacate. The physical properties and performances of synthetic lithium complex grease with optimum formulation were investigated by the ASTM and KS methods. The results of dropping point, penetration, oil separation and four ball E.P/wear tests were obtained.