Abstract: 3D stitched composites overcome the disadvantage of weak interlaminar properties of 2D lay-up composites, and in the aerospace industry, the geometry of 3D stitched preforms, as the core reinforcing element of composites, plays a crucial role in the mechanical properties of the material. However, as the preform is essentially a flexible fabric, it may experience geometrical changes during the stitching process, such as yarn path shifts at the stitch holes and compressive deformations in the cross-section. In order to accurately predict and design the properties of composites, it is crucial to achieve accurate and high-fidelity modelling of preforms. In this study, a simulation stitching process was developed to address the complexity of the fiber structure in quartz fiber 3D stitched preforms using virtual fiber technology. The simulation method was able to accurately model the dynamic motion and deformation process of the yarn and successfully constructed a geometric twin model of the preform, and the internal single-cell structure of the preform samples was analyzed in detail using micro-computed tomography (Micro-CT), which in turn confirmed the accuracy and stability of the established model.