We analyzed the variation trend in radial increment of Populus euphratica under conditions of long-term zero flow in the lower reaches of the Tarim River through methods of wavelet analysis and Mann-Kendall, Mann-Whitney trend test. The results are as follow: (1) Benign changing of tree-ring width in the lower reaches of the Tarim River occurs because of the ecological water conveyance. (2) There is a slowly decreased trend in radial increment of Populus euphratica in Yinsu, Kardayi, Alagan and Yiganbjm transects, because of the zero flow in the lower reaches of the Tarim River in 1970-1999, the whole variation is a long-term and slow process, rather than rapid changes, nor has the mutation. (3) There is a short-term and mutation influence in human factors on radial increment, such as the ecological water conveyance. (4) Compared with the zero flow condition, under the condition of non-zero flow, the regular alternate trend of rise and fall presented in tree-ring width in 1970-2009; Under long series (1962-2009), tree-ring width variation takes on 25-year cycle, large cycle (25-year) include small cycle (11-year and 5-year).