Taking the Lower Silurian Longmaxi Formation in the Changning area of the southern Sichuan Basin as an example, the characteristics and formation stages of tectonic fractures are comprehensively studied by regional scale geological analysis and microscopic scale experimental tests. Regional scale geological analysis shows that there are mainly high-angle and vertical structural fractures, which have the characteristics of small opening, large spacing, small fracture density, and high filling degree. The fracture systems can be divided into three stages and six groups, which correspond to the structural compression in the near south-north, northwest, and northeast directions. The microscopic scale experimental test analysis confirmed that the formation of tectonic fractures mainly experienced three stages of tectonic movements, namely, the Middle-Late Yanshanian tectonic movement (136-94 million years ago (Ma)), the Late Yanshanian tectonic movement-Early Himalayan tectonic movement (94-67 Ma), and the Middle-Late Himalayan tectonic movement (67-0 Ma). The corresponding uniform temperatures of the fracture filling inclusions are 118.5-140.2, 91.6-108.5, and 73.2-82.2 degrees C, respectively. Based on the tectonic analysis and geomechanical principles, an evolutionary model of structural fractures was established. Fractures with early formation and high filling degree and fractures with late formation but large angle between the fracture orientation and current geostress direction are beneficial to shale gas enrichment.