Abstract: During the 1950s, the theory of "China's oil poverty" was prevalent in academic circles, placing China's oil exploration efforts under dual pressures from both theoretical direction and resource demand. Based on valuable historical materials such as correspondence, manuscripts, conference speeches, and academic works produced by Li Siguang during his tenure as Minister of Geology, this paper systematically examines the course of his practical application of geomechanics theory to guide China's offshore oil exploration from 1954 to 1971. The study finds that Li Siguang did not confine himself to the traditional debates over hydrocarbon origin theories. Instead, based on the controlling patterns of oil and gas resources in eastern China as revealed by the Neocathaysian structural system, he proposed a strategic vision of "balanced development between eastern and western regions, with simultaneous advances on land and at sea." He also established the guiding principle of "first identify oil-prone regions, then locate oil fields, "He thereby constructed and put into practice a comprehensive methodological system for petroleum survey and exploration. Following the breakthrough at the Daqing Oil Field, Li Siguang personally oversaw the formulation of a "from land to sea" progressive strategy. Starting with the Bohai Sea, he systematically planned the layout for oil and gas exploration across China's entire maritime territory and issued the strategic call to "march toward the ocean." This practical experience not only laid a solid theoretical and practical foundation for the inception and development of China's offshore oil industry but also provides a historical reference for understanding the logic behind national strategies such as achieving scientific and technological self-reliance and ensuring energy and resource security.