A strain of bacteria able to produce biosurfactant was isolated from oil-polluted soils. It was identified as Aeromonas sp.. The biosurfactant in fermentation broth was able to reduce the surface tension of water from 70.2mN/m to 28.9mN/m and showed great stability against temperature, pH and mineralization. The biosurfactant could stabilize the broth over 85% for 350h. The optimal carbon source for fermentation of the biosurfactant was 2.0% glycerol..NO₃^- or NH₄^- as nitrogen source had no difference for biosurfactant production. The biosurfactant was extracted from fermented broth and analysed by TLC. Analytic results showed that this biosurfactant was a kind of glycolipid.