In order to avoid inaccurate stresses of simplified carcass and zeta layers resulted from the traditional numerical method, a numerical method to predict the behavior of unbonded flexible risers was presented by taking complicated crosssections of carcass, zeta layers and interaction between all layers into consideration, which not only made the finite element model highly consistent with the real geometrical shapes of layers, but also had high efficiency and precision. The numerical method could effectively conduct stress evaluation of carcass, zeta layers, failure modes and interaction between all layers. The behavior of an eightlayer unbonded flexible riser under axial compression was predicted. It is shown that numerical results are in good agreement with theoretical results; tensile armor layers are the main bearing layers; compressive stiffness is much smaller than tensile stiffness; and boundary conditions have little influence on the compressive property.