Abstract: Making 2003 as cut-off point, based on annual rainfall and runoff material of Jinshajiang basin from 1956～2014, the trend change of rainfall-runoff before and after impoundment of TGP are quantitatively analyzed.Runoff replenished by rain of after the impoundment of TGP and compared with the measured runoff,it quantitatively analyzed the influence of surface condition change to runoff with the invariant climate condition.