Abstract: The control effect of Agave sisalana Perrine leaf extract on mango anthracnose Colletotrichum gloeosporioides Penz. was studied in this paper. The results showed that growth rate and quantity of mycelia were suppressed obviously by the extracts. When 0.2 mL extracts were added to 100 mL culture media, the mycelia growth rate was 50%. When 5 mL extracts were added to 100 mL PDA, the restraining rates of proliferation and germination were 98.18% and 97.43% respectively. When the mycelium was treated directly by the extracts, the electric conductivity of handling liquid was increased, which meant the cell structure of mycelia was break down and electrolyte leakage. The mango plants were treated by the extracts at the 21 d, the seedling disease incidence of control plants was more than 92.22%, but the treated plants' was just 44.44%. So the extracts of A. americana could control C. gloeosporioides effectively.