In this study, a micromechanical method is presented to study working temperature variation effect on biaxial failure envelopes of continuous fiber-reinforced composites with imperfect interfacial bonding. Generalized viscoplastic potential structure model is used to describe nonlinear response of composites. The interfacial debonding model is incorporated into the micromechanical model for describing the interfacial damage evolution. Theoretical results show good consistency with experimental data. On this basis, a series of numerical examples are performed to investigate working temperature variation and interfacial debonding effect on macroscopic tensile response and biaxial loading failure, respectively. The results indicate that the stress-strain responses and failure strength are closely dependent on working temperature. And biaxial compressive loadings in axial-transverse and transverse-transverse, as well as axial tensile and compressive loadings, do not generate interfacial debonding.