Abstract: Ammonia oxidizing bacteria (AOB) play an important role in global nitrogen cycle. This paper reviewed the research advances on molecular ecology of ammonia oxidizing bacteria. The analysis of systematic evolution of AOB based on 16S rRNA reveals that the evolution of AOB is quite simple, which belongs to β and γ subgroup of Proteobacteria. This paper also introduced the main molecular ecological methods in the study of AOB, which included denature gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP), fluorescence in situ hybridization (FISH), and realtime PCR, summarized the effects of ecological factors on the communities and populations of AOB, and prospected the research directions on molecular ecology of AOB.

Key words: maize straw, stubble height, straw-returning, winter wheat farmland, soil respiration.