Abstract: This study investigates the mechanical behavior of the transverse tensile properties of unidirectional carbon fiber-reinforced epoxy resin composites with varying fiber and void volume fractions, focusing on the influence of temperature and void volume fractions. For this purpose, an algorithm based on the maximum offset method for the generation of representative volume elements (RVE) was developed. A series of high-fidelity RVE models were constructed for unidirectional composites with different fiber and void volume fractions. To address the localization problems in damage models and to overcome the inefficiency of traditional finite element methods (FEM), a coupled non-local damage model with fast Fourier transform (FFT) computational framework was proposed. After comparative analysis with reported models and results, the proposed computational framework was validated to have good accuracy and reliability. Based on the validation, we investigated the influence of temperature, void and fiber volume fraction on the transverse tensile performance of composites. Specifically, elevated temperatures correspond to a decrease in the transverse tensile strength and modulus of the composites. In addition, an increase in voids results in a significant reduction in both tensile strength and modulus. Furthermore, as the fiber volume fraction increases, the transverse modulus of the composite material increases significantly while the tensile strength remains relatively constant. The computational framework and research findings presented in this study are expected to play a significant guiding role in the design and manufacturing of composite materials, aiming to enhance material performance and reliability.