Based on Duncan-chang E - B material model and used the finite element software ADINA, the paper conducted stress and deformation finite element calculation on an asphalt concrete rockfill dam so as to study the dam''s stress strain characteristic. based on the result of the calculation, it carried out sensitivity analysis on the Duncan-chang E - B material model parameters of asphalt concrete core wall ,such as Young''s modulus of elasticity,cohesion,bulk modulus . The finite element calculation results of the dam show that there has been tensile stress near the small range of upstream and downstream dam slope; dam stress becomes a mutation and appears an arch effect near the core wall; each parameter''s change has different degrees of influence on the stress and deformation of the core wall, which Young''s modulus K, Young''s modulus index n belong to high sensitivity parameters, and bulk modulus index m to low sensitivity parameter. In order to ensure dam safety, slope protection measures must be taken in the upstream and downstream dam slope. At the same time , the compaction standard of dam body near the upstream and downstream dam slope should be inhanced in the dam filling construction period; the asphalt concrete mix proportion should be appropriately adjusted in order to ensure the safety and stability of the core wall and according to the test calculation to adjust the core wall deformation modulus and make it coordinate with the transition material''s modulus and minimize the negative effect of settlement difference.