At present some 300m level high rockfill dam with core wall is to be built in our country. Under the high stress status, the dam materials are made of gravelly soil whose long-term deformation characteristic can affect rockfill dam with core wall greatly. In order to study the effect of creep characteristic of gravelly soil core wall on the rockfill dam with core wall, the nine parameter power series constitutive model and its test parameters are adopted, and the filling and creep process of 300m level high earth core dam are simulated by FEM. The creep displacement is about 47 cm . When considering creep, displacement would reflect the actual operation situation of dam.