Abstract: On December12, 2014, Middle-Route Project of South-to-North Water Diversion was formally put into operation, and since then, the influence of water diversion on the hydrological regime of the middle and lower reaches of the Hanjiang River has appeared gradually. In order to better research the water diversion influence, this paper uses the flow data at Huangjiagang, Huangzhuang and Xiantao Hdrological stations from 1990 to 2016 to analyze the change of characteristic discharge in the middle and lower reaches of the Hanjiang river before and after water diversion and use Mann-Kendall nonparametric test to conduct trend test and mutation test. The results indicate that the average annual flows and dry-wet rates for different periods show a decline trend, the annual flow mutation is in 2014; the annual runoff distribution become more uniform (the annual runoff concentration and relative variation rate become smaller). It is shown that water diversion has obvious influence on the hydrological regimes of the middle and lower reaches of the Hanjiang River and related departments should take corresponding measures.