Abstract: The concrete dam displacement is studied considering the factors such as foundation modulus increasing with depth,seepage coefficient reducing as depth,seepage coefficient anisotropic,curtain and drainage in the dam heel and seepage field and stress field coupling. Some conclusions are obtained： if the foundation is considered only with the seepage volume load,the dam top horizontal displacement of the reference base point develops upstream. When the foundation size increases,the reference base point′s horizontal displacement increases. However,the value measured by the reversed pendulum anchored to the rock foundation is often regarded to be absolute displacement. The above practice is estimated to be limited when the water load on the dam foundation is taken into account. It is proposed that the displacement of the reference base point should be considered,in order to obtain accurate inversion value of parameters. The parameter back analysis needs to adapt to the relative displacement value of dam crest and base point calculated by the infinite element numerical computation,together with the measured component of water pressure from displacement.