Abstract: Microbial metabolism can produce biosurfactant, which have potential for biological treatment of marine environmental pollution. An Arthrobacter globiformis strain S-22 was isolated from the offshore seawater of Qingdao. The optimum conditions for its growth and production of biosurfactant were determined by shaking flask experiment. The surface tension decreased to 30.5 mN/m at optimum condition in 6 h. The synthesis of biosurfactant was fast in strain S-22, which was helpful for large scale industrial production. The results of TLC, FT-IR and GC-MS analyses showed that the biosurfactant was a glycolipid composed of trehalose and two fatty acids (hexadecanoic acid and 9-octadecanoic acid). The trehalose lipid, whose critical micelle concentration was as low as 48.5 mg/L, had a fine emulsification capacity with high surface-activity and strong endurance to heat and salts.