Abstract: In order to understand the spatial and temporal distribution of anammox bacteria（AnAOB）in the sediments of Xiangxi River in the Three Gorges Reservoir Area，the abundance of AnAOBwasdetected by real⁃time quantitative PCR（qPCR）in the sediments of the five sites of Xiangxi River，and the influence of physicochemical factors on AnAOB abundance was analysed by Spearman rank correlations. The results showed that AnAOB existed in the sediments of Xiangxi River，and its abundance was between 1.45×104-3.16×109 g-1sediment. The number of AnAOBs varied greatly at different sites. In terms of time（0-10 cm in 2016），the AnAOB abundance of the five loci was highest in autumn，and the sites（a and e）showed the same distribution pattern，namely autumn>winter>spring>summer. In terms of space（0-2 cm in 2016），AnAOB abundance was highest at the site（e）in the spring and winter，and highest in the site（d）in the summer and autumn. In spring of 2017，AnAOB abundance was b>a>e>c>d，e>c>d>a>b in summer，c>d>e>b>a in winter；As the sediment depth increased，the AnAOB abundance increased firstly and then decreased in the d and e sites（0-10 cm）. Spearman rank correlations confirmed that AnAOB abundance was significantly correlated with total nitrogen（TN）（P<0.01），nitrate nitrogen and total organic carbon（TOC）（P<0.05）concentrations of insediments. AnAOB abundance under different physicochemical factor and seasons showed no significant difference by two-way analysis of variance（P<0.05）.

Key words: AnAOB, real?time quantitative PCR, temporal and spatial distribution