The Yellow River has experienced significant changes in hydrological regime in recent 40 years. These changes have serious implications for water and soil losses, ecologic crisis, and economic losses. The changes of of runoff regime in the Chahagou Basin during the period from 1956 to 1999 have been studied. The results indicate that a significant change point of runoffappeared in 1978, and the change mainly due to soilwater conservation measures. The average annual runoffreduced by 30% was compared with that in the period before 1978. The reduction of the annual runoffwas associated with the decreased interannual and intraannual variability in runoff. In addition, the hydrological regime of the basin changed consistently with the up and down progress of sediment-trapping dams.