To analyze by comparison AOB amoA gene diversity of three cultivated soils, i.e. black soil in Hailun (HL), chao soil in Fengqiu (FQ) and red soil in Yingtan (YT) which are located in different climatic zones in East China. Total DNA of soil microbe was extracted by the direct lysis method, and amplified with specific primers of AOB amoA gene, amoA gene libraries of the three soils were thus constructed and analyzed with the RFLP method for diversity. The number of clones in amoA gene library was 49, 50 and 48 in HL, FQ and YT respectively, and their corresponding number of OTU (Operational Taxonomic Unit) was 10, 10 and 14, of while 4 were common in all the three samples. YT was the highest in index of amoA gene diversity while FQ the lowest; The similarity index between HL and FQ in AOB community was 70%, between HL and YT was 50%, and between FQ and YT was 42%, which indicates that AOB distribution has geographic characteristics. Seventeen AOB amoA gene sequences could be sorted into six clusters belonging to two genera, Nitrosospira and Nitrosomonas. All the three soils have an abundance of AOB, thus implying autotrophic AOB play a crucial role in nitrogen cycling in cultivated soils.