The aimed of this study was to examine the effective of antagonistic actinomycetes isolates in prevention of Xanthomonas oryzae pv.oryzae (Xoo) caused bacterial blight disease on rice and determine the characteristic of some actinomycetes isolates. One hundred and sixteen actinomycetes isolates were collected from rice field in some provinces of Mekong delta that were determined antagonistic ability against Xoo. The results showed that, 23 of 216 isolates in total have ability against Xoo. Determination antagonistic ability of 23 actinomycetes isolates in controlling Xoo with five replications, the results showed that 4 isolates HG3, HG37, ST12 and VL10 have high antagonistic ability with radiuses of inhibition zones reaches 6.30 mm, 6.60 mm, 5.20 mm and 6.14 mm, respectively at 2 days after inoculation. In addition, cellulase activity assay on CMCmedium found that 4 actinomycetes isolates HG3, HG37, ST12 and VL10 have expressed the cellulolytic activity, with the cellulose lyses halo from 12.2 mm to 13.5 mm at 6 days after testing.