Five different concentration of 10% allicin microemulsion were used to control watermelon anthracnose.The result of laboratory and pot experiments showed that all different concentration treatment of 10% allicin micro-emulsion had control effect to colletotrichum lagenarium in watermelon. The suppression ratio of mycelium growthrate methods were 89.80%, 76.00%, 61.03%, 51.63% and 14.97%, respectively. The suppression ratio of isolatedleaf indoors by pathogen inoculation were 81.81%, 64.02%, 59.10%, 51.14% and 1.82%, respectively. The controlefficiency to pathogen inoculated at the seedling stage through pot culture experiments were 91.17%, 75.72%,61.68%, 43.53% and 4.56%, respectively. In conclusion, using 10% allicin microemulsion 300～500 times solutionin production can effectively control the spread and development of watermelon anthracnose.