Abstract: The monotonic tensile and uniaxial ratcheting behaviors of T6-treated SiCP/6061Al alloy composites were numerically simulated at 300℃ by using ABAQUS and employing a single-particulate cell model of the composites and 2-D axi-symmetrical 6-node element. In the simulation, a new unified visco-plastic constitutive model, which simulated the ratcheting of the material reasonably, was proposed to describe the time-dependent cyclic deformation behavior of the matrix. It is shown from the simulations that the finite element model proposed in this work simulates the uniaxial ratcheting of the composites and its time-dependence, and the simulations agree with the corresponding experiments well. It is also shown that the cyclic deformation of the composites is heterogeneous and complicated in meso-scale.