Abstract: In order to solve the complex nonlinear problem conveniently, the unified nonlinear constitutive model considering strength-differential effects of fiber reinforced resin matrix composites was proposed firstly. Then, the three-dimensional expression form of the constitutive model was deduced ulteriorly on the basis to be appropriate for the development of nonlinear finite element analysis tool. After that, using user-defined subroutine UMAT which was provided by finite element program ABAQUS, elastic-plastic stress analysis program in cases of two-dimensional and three-dimensional was self-compiled. Finally, the prediction and testing results of stress-strain curves for unidirectional composite laminates and angle-ply composite laminates under off-axis tension/compression were compared using the program, the elastic-plastic problems of composite cantilever beams were discussed, and the differences of stress distribution and deflection response between the cases of with and without considering strength-differential effects were analyzed and compared. The results show that using the proposed constitutive model to analyze the elastic-plastic deformation considering tension and compression asymmetric problems is quite efficient. The constitutive model is expected to become the practical numerical analysis tool, thus guides engineering practices.