Abstract: In order to control Fusarium isolated from shrimp culture environment producing T-2 toxin,the inhibitory effect and antibacterial mechanism of lipopeptides from Bacillus natto on Fusarium was studied in the article.The inhibitory effect was studied through the influence of lipopeptides on the germination and growth of Fusarium spores; and the observation of the ultrastructure of the spores,the mycelium morphology and the mycelium permeability was performed through electron microscope,ordinary microscope and fluorescence microscope respectively to study the antibacterial mechanism.When the concentration of lipopeptides was 1 mg/mL,the inhibition rate on the germination of Fusarium spores reached 78.8%,and the cultivation biomass of Fusarium was 24.5% of the control group without lipopeptides on the third day.Under the condition of the same concentration,the microscopic observation under scanning electron microscope revealed that the spores of Fusarium presented moniliform state under the influence of lipopeptides; ordinary microscope revealed that the mycelia became nonseptate after the treatment of lipopeptides; and fluorescence microscope revealed that lipopeptides could increase the membrane permeability of the Fusarium mycelium.