Stress and deformation properties and hydraulic fracture under the state of static force are the key problem of design and construction for high earth-rock dam. Taking a 127.5m high earth-rock dam for example, the paper got the index of physical properties and Duncan-Chang E-B model parameters of dam material through the laboratory experiments and triaxial tests, and computed the stress and deformation and seepage quantity of high rock-fill dam with composite geo-membrane during the period of completion and seepage stabilization by use of finite element method. It also judged whether the hydraulic fracturing of the core wall took place. The calculation results show that because of the rheology of rockfill material, vertical and horizontal displacements of dam are taken place. The composite geo-membrane has an evident effect on reducing embankment seepage, decrease pore water pressures and saturation line of embankment dam, and prevent the hydraulic fracturing produced in dam body compared with clay core wall.