Abstract: Reliable numerical simulation results depend on the use of accurate numerical models. Micro-computed tomography (Micro-CT) technology is capable of non-destructively imaging the internal structure of composite materials, hence, numerical models reconstructed from it are more representative than the idealized ones. Here, a review is presented for constructing mesoscopic models of composite materials based on Micro-CT images and its application in virtual testing. A novel concept, Micro-CT aided numerical simulation, is proposed. First, the principle of Micro-CT imaging, the characteristics of equipment, and the difficulties with scanning fabric-reinforced composites are discussed. Second, the characteristics of existing Micro-CT aided modeling techniques are analyzed and compared. The models are divided into three types including indirect, voxel, and digital material twin ones. The theoretical basis and technical approaches for constructing each type of model are highlighted, and the advantages and limitations of each are analyzed. Then recent applications of Micro-CT aided numerical simulation in composite molding process and mechanical property prediction of fabric reinforced composites are summarized, showing the potential and importance of the technology. Finally, the future of Micro-CT aided numerical simulation technology is anticipated.