The objective of this research was to investigate the effective of antagonistic actinomyces isolates in prevention of Colletotrichum sp. fungus caused anthracnose disease on Nasturtium. One hundred and sixteen actinomyces isolates were collected from Nasturtium field in some provinces of Mekong Delta that were determined antagonistic ability against anthracnose  fungus. The results showed that 22 of 116 isolates in total have ability against anthracnose fungus. Determination antagonistic ability of 22 actinomyces isolates in controlling anthracnose fungus with five replications, the results found that 2 isolates ĐT4 and VL2 could reduce mycelia growth of anthracnose fungus with radiuses of inhibition zones reaches 6.00mm and 6.50mm and antagonistic efficacy 62.22% and 65.83%, respectively at 7 days after inoculation. On the other hand, chitinase activity assay on chitin medium found that 3 actinomyces isolates ĐT4 and VL2 have expressed the chitinolytic activity, with the chitin lyses halo radius of 16.82mm and 16.27mm respectively at 5 days after testing.