Expanded polytetrafluoroethylene ( ePTFE ) membranes, with their unique microstructure and porous architecture, find extensive applications in biomedicine, industrial filtration, textiles, and apparel. However, previous studies have predominantly focused on the effects of applied stress and mechanical stretching on the morphology of ePTFE membranes, neglecting the influence of the crystal structure itself on the membranes. Therefore, this study systematically investigated the effects of PTFE microcrystalline structure variations on paste extrusion behavior, high-temperature mechanical properties of calendered films, and morphological structure of ePTFE membranes using three PTFE dispersion resins with distinct microcrystalline structures. Results indicate that PTFE resins with high crystal folding and defect levels exhibit lower extrusion pressure and shear viscosity. Calendered films made with these resins require the lowest energy barrier to overcome during stretching and perforation, resulting in the lowest tensile and yield strengths. By further regulating the initial crystallinity and crystal size of PTFE, ePTFE membranes with distinct morphologies and porosity characteristics were prepared. This approach can effectively control the formation of fibrils within the ePTFE membranes, enabling the targeted design of pore size ( 0.47 ~ 0.8 μm) and porosity ( 47% ~ 58% ). This study provides novel insights and methodologies for understanding the multiscale structural evolution of PTFE resin during processing, as well as the formation mechanisms and control strategies for ePTFE microporous structures.