Abstract: This paper highlights the reserves study and the geological understanding of Qaidam basin, reviews the consideration and thought way for petroleum exploration in different periods, displaying the development courses from the simple to the complex targets for exploration, from the outcrop to the buried geological structures, from the superficial (phenomenon) to the deep (essence) in understanding, from imprecise to precise in reserves study, from qualitative to quantitative assessment, from small to large amount of reserves, and from small-sized gas pool toward large sized gas province. The study has an active and significant value for reference and guidance to the petroleum exploration and reserves study of other similar sedimentary basins.

Key words: Qaidam basin, Quaternary, biogas, exploration course, reserve state