Denitrification occurring mostly in flooded soil is considered as an important process which reduces use efficiency of soil nitrogen and affects environmental quality.In this study, 3 strains of denitrifiers were isolated from soil.Of the 3 strains, one is obligate aerobic bacteria coded as AD26, the other two strains are facultative bacteria coded as AD7 and AD60.Based on the morphological, physiological, and biochemical features of the three isolated strains, they were identified as Pseudomonas sp.In an aerobic incubation trial, N denitrification loss in the liquid culture medium inoculated with AD26 and AD7 reached to 21% and 18%, respectively, in 24 hours.In an aerobic soil incubation trial, about 56% of the soil nitrate2N was lost in the first three days due to denitrification in the presence of AD26 or AD7.Moreover, soil nitrate was eventually transformed into nitrogen oxide or N₂, leaving no nitrite left in accumulation.Therefore, the bio2denitrification in the farmland should not be overlooked.