The first impoundment of the Three Gorges Dam reservoir in China started from a water surface elevation of 95 m on June 1, 2003 and reached 135m on June 15, 2003. After that, an intensive rainfall lasted nearly a month, Qianjiangping landslide occurred on the early morning of July 14, 2003 and caused great loss of lives and property. In order to study the influence of impoundment and rainfall, based on the coupling model of runoff and infiltration, the seepage and runoff of the landslide during impoundment and rainfall were simulated. The results show that the toe of slope are immersed because of the change of reservoir water level, the suctions of sliding mass and sliding zone on upper slope are decreased and the runoff occurs because of intensive rainfall. These are inducing factors of the landslide. The results are useful to study instability mechanism of the landslide.