This paper analyzed the inner-anmual,decadal and annual nunoff variation characteristics in the watershed above theDanjiangkou Reservoir based on the runoff data during 1930-2018. Then Mann -Kendll trend test method and Sen's slopeestimation method were used to evaluate the variation trend of runoff.Meanwhile,the runoff correlations betwen summer andautumn seasons were examined based on the non-parametric corelation coefficienks。The resuls show that the nunoff present anon-significant descending trend in both seasons. The runof of summer flood season has an obvious positive corelation to that ofautumn flood season，and the years of positive correlation had exceeded more than half during 1930-2018.