Polypropylene microporous membranes made by dry process are mostly used for separators in Lithium batteries, which require high porosity and strong mechanical properties. How to produce microporous membranes with high performance is an ambiguous question both in industry and academia to cater the development of electric vehicles. In this work, efforts are made to answer the question from the following two aspects: (a)For the preparation of precursor films, with the aid of small and wide angle X-ray scattering measurements as well as tensile analysis, the key processing and structure parameters of polypropylene precursor films are identified. Besides, pore formation is firstly analyzed semi-quantitatively with the key structural parameters, i.e., orientation parameter, lamellar thickness, and amorphous thickness, and other parameters of precursor films from a theoretical point of view. (b)As for the post-stretching process, the intrinsic deformation mechanism of oriented lamellar stacks in precursor films is studied at different temperatures with ultrafast in-situ X-ray scattering. Based on the crystal morphology and structural evolution, the main deformation mechanisms in three temperature regions around yield are defined as elastic deformation, crystal slip, and melting and crystallization, respectively. In addition, for better understanding the structural evolution during casting, a laboratory extruding-casting machine is designed and constructed to carry out in-situ small and wide angle X-ray scattering measurement for casting experiments.