The ecological distribution of denitrifying bacteria in the three soils on rhizoplane and in rhizosphere of rice and barley was studied.Results showed that the total amount of bacteria was larger on rhizoplane than in rhizosphere and non-rhizosphere soil in each growing period of rice.The ratio of R/S was above 10-100.The total amounts of bacteria or denitrifying bacteria in rice and barley rhizosphere attained to the maximum during heading period,however,there was a marked dropping in ripening period.It was clear that the amount of bacteria in rhizosphere of rice was higher than that in rhizosphere of barley in each corresponding period.