This book analyzes the formation and evolution of the giant hydrocarbon reservoirs based on major basins onshore China. It discusses exploration and research advantages of major basins in China, such as Sichuan, Tarim, and Ordos Basins and also systematically analyzes and summarizes the formation conditions, distribution rules, and main controlling factors of deep oil and gas fields. On this basis, it forecasts the exploration prospect of China's onshore deep oil and gas, providing theoretical guidance and technical support for deep oil and gas exploration breakthrough and large-scale reserves growth. This book focuses on the analysis and discussion of hydrocarbon generation mechanism of deep-paleo source rocks, discusses the accumulation rules of cross-structural reservoir formation and oil-gas enrichment in ancient strata, the combination of gypsum-salt rocks and carbonate rocks, the potential of oil and gas accumulation under salt, the main controlling factors and distribution rules of deep oil and gas fields, and preliminarily grasps the geological understanding of the formation and distribution of deep-large oil and gas fields, namely ①abundant hydrocarbon supplied by two types of source kitchens, ②three large-scale lithologic reservoir rocks, ③hydrocarbon accumulation controlled by three paleoes (paleouplift, paleoplatform margin, and paleofaults), and ④reservoir formation across major tectonic periods. The book serves as a guidance for both researchers and students majoring in petroleum geology and other related fields.