Diversity and its spatial distribution of bacteria in 0～5 cm,5～10 cm and 10～15 cm depths of non-tillage paddy fields were studied based on the molecular method of ARDRA(amplified ribosomal DNA restriction analysis).Results indicted that in different soil layers of the paddy field,bacteria were very high in species diversity,which,however,varied from layer to layer due to differences in soil moisture,soil depth,soil temperature,daylight and some other factors.Bacteria in the surface layer were the highest in species diversity,but without a dominant genotype.They were relatively low in species diversity in the 10～15 cm soil layer,but they did have some dominant genotype.Bacteria communities in different soil layers showed little similarity.The Jaccard index was 20.65% between the bacterial clones libraries of the 0～5 cm and 5～10 cm soil layers; only 8.31% between those of the 0～5 cm and 10～15 cm soil layers and 38.75% between those of the 5～10 cm and 10～15 cm soil layers,indicating complexity of the structures of soil bacteria communities and spatial segregation in the soil.