The objective of this study was to estimate the ability Chlorpyrifos ethyl (CE) decomposition with and without supplementation of organic acids in anaerobic conditions by soil bacteria on intensive rice fields in the the Hau Giang provinces. The experiment was set up in microcosms containing mineral minimum (30 ml), soils (10 g) and CE (35ppm) in 15 months days at anaerobic conditions. The results showed that all treatments were well biodegradable for CE. After 2 months of incubation, the concentration of CE rest of the treatments ranged from 3-82% of the initial concentration. CE decomposition rate was increased after supplementation CE. After 11,6 months of incubation, CE concentrations rest of the treatments ranged from 4-57% of the initial concentration. Bacterial communities (PH02) have higher CE decomposition rate than other bacterial communities under the same conditions supplemented with organic acid. Meanwhile decay rate among the microbial communities in the absence of additional organic acids is the same. Intermediate products generated during the decomposition of CE by soil bacterial communities were determined to include O,O-dietyl-3, 6-dichlo-2 pyridil photphorothioat, 3,5,6 trichloro-2 pyridinol (TCP) và O,O-diethyl-O (3,5,6-trichloro-2-pyridyl) phosphate (Chlorpyrifos oxon). PCR-DGGE results showed that the structure of bacterial community (PH01) diversity among treatments complements, does not supplement the organic acid and the control treatment (no additional Chlorpyrifos ethyl) has a high degree of similarity, 90 -96%.