Abstract: Oil and gas are strategic minerals concerning the lifeline of national economy and national security. China's oil and gas exploration has entered a new stage featuring deep strata, subtle reservoirs, low permeability, unconventional resources and deep-water marine fields, which is characterized by great exploration difficulty, high risks and insufficient commercial investment, so it is urgent to take the public welfare oil and gas geological survey as the pioneer to read the exploration work. The authors in this paper systematically expounded the connotation, positioning, core functions and basic conditions of public welfare oil and gas geological survey, and analyzed the internal demands from national energy security, supply-demand contradiction, reserve and production increase, and mining right reform. Besides, the major achievements of the conventional oil and gas in new strata of the northern exploration areas, the shale gas in the sttucturally complex southern regions, the continental shale oil in Songliao Basin, and other unconventional oil and gas were summarized, and the overall tasks and seven key directions in the new era were clarified. The evaluation of block evaluation for mining night withdrawal, investigation positioning, scientific and technological innovation and working mechanism were put forward. The results showed that public welfare oil and gas geological survey had significant advantages in resource foundation, practical experience, scientific and technological support and institutional guarantee, which is a fundamental, pioneering and strategic work to break through exploration bottlenecks, support block transfer, guide commercial exploration and ensure national energy security. Adhering to basic research, strengthening scientific and technological innovation, innovating working mechanisms and serving the market will strongly support the increase of oil and gas reserves and production and the independent control of energy in China.