Abstract: Torbanite is a typical oil shale rich in Type Ⅰ organic matter, with its biological precursors primarily being Botryococcus braunii race A. It is characterized by an overwhelmingly dominant aliphatic structure and low primary thermal maturity, making it an ideal end-member sample for conducting fundamental research in petroleum geochemistry. Taking the Permian torbanite from southeastern Australia as the research object, metal-tube pyrolysis simulation experiments were conducted in a closed system. The geochemical characteristics of gaseous hydrocarbons, liquid hydrocarbons, and solid residues during thermal evolution were systematically analyzed, and the genetic mechanisms of carbon isotope reversal in highly mature natural gas were explored. The research results show that hydrocarbon generation simulation experiments using high-quality end-member samples can reveal abundant geochemical information, which is of great significance for improving petroleum geochemical theories and enhancing the scientific nature of hydrocarbon exploration and resource evaluation.