Abstract: Sanmenxia basin is a small Cenozoic-dominated rift basin in the southern margin of North China Block, and 2D seismic and drilling work of oil and gas exploration has been conducted since the 1950 s. Significant progress was made in 2023, and three exploration phases were divided for 70 years of exploration, including petroleum prospecting and basic geological survey, public-benefit oil and gas geological survey, hydrocarbon breakthrough and resource potential assessment. In recent years, Paleogene hydrocarbon source rocks were identified in the southern basin through public-benefit oil and gas survey, and advanced understanding of hydrocarbon accumulation was obtained. Well Yuxiadi-1 was strategically deployed in Hanguguan structural belt to further evaluate oil and gas potential, and five oil-bearing layers were revealed through logging interpretation. Stable industrial oil flows were obtained during multi-layer testing, marking a historic breakthrough in Sanmenxia basin. Preliminary estimate of the basin's prospective geological resources has been made. Five critical insights emerge from exploration history and oil breakthrough. ① Meticulous field observations enable source rock identification. ② Integrated data analysis enhances fundamental petroleum geology research. ③ Cost-effective technical approaches have been explored, the anderstanding has been deepened and the cloubts have been verified; ④ Synergized geological-engineering integration accelerates discoveries. ⑤ Collaborative central government-local government-enterprise exploration model optimizes resource evaluation. As a representative of China's numerous under-explored medium-small basins, Sanmenxia's rapid transition from source rock discovery to commercial flow achievement boosts confidence for the neighboring basins like Weihe basin and the Southern North China basin, and provides valuable guidance and references for hydrocarbon exploration in structurally similar small-medium basins nationwide.