The research was conducted at laboratory and greenhouse of Plant Protection Department, College of Agriculture and Applied Biology, Can Tho University in order to determine morphological characters and evaluate the pathogenicity of Colletotrichum spp. to cause the anthracnose disease on Gac and screening the effective antagonistic actinomyces isolate in prevention of anthracose disease. The results showed that there are 9 different isolates Colletotrichum spp. and 120 actinomyces isolates were colleted from different provinces In Mekong Delta of Vietnam. Examination pathogenicity of 9 isolates of Colletotrichum spp. caused anthracnose disease on Gasc in the greenhouse conditions, results showed that Col.CT3 was collected in Can Tho gave higher infection. Detemination the antagonistic ability of actinomyces isolates against anthracose disease fungus in the in vitro condition. The results showed that, there were 36 isolates actinomyces expressed antagonistic ability. Both isolates NCT.TG4 and GCT.TG9 showed highest inhibition zones with 6,2 mm and 4,4 mm respectively at 3 days after inoculation in comparison with the others.