The development of petroleum generation simulation for lacustrine source rocks has evolved through three distinct stages: high-temperature simulations, limited-space simulations, and simulations under geological conditions. Increasing emphasis is being placed on techniques that more accurately replicate real geological environments. Notably, the catalytic effects of the “geological molecular sieve,” a complex formed by organic matter, clay, and metal elements, have become a key area of focus. Building on an analysis of the “geological molecular sieve” characteristics in Chinese lacustrine source rocks, the research team systematically conducted medium- and low-temperature catalytic petroleum generation simulation experiments. The experimental products closely mirrored those formed under actual geological conditions. The observed changes in oil and gas yields highlighted the catalytic role of the “geological molecular sieve,” which enhances petroleum and hydrocarbon evolution at low temperatures and accelerates gas formation processes at medium temperatures. This chapter provides a detailed account of the experimental findings, offering valuable insights into medium- and low-temperature catalytic petroleum generation processes and their implications for understanding hydrocarbon generation mechanisms.