In the past over 50 years of offshore oil-gas exploration practice, technological innovations and progresses in this regard in China have made great progresses with many major breakthroughs. Especially, since 2011, it welcomed a quick development. In 2010, the annual offshore oil-gas production of China exceeded 50 million tons of oil equivalent, including more than 30 million tons of crude oil from the Bohai Basin, which realized the goal of building an "Offshore Daqing", and oil-gas production in China’s sea areas has been growing rapidly. In this review, we systematically summarized the basic petroleum geological features of China offshore oil-gas resources in terms of petroliferous basin sedimentary characteristics, tectonic structure types, genetic types of oil and gas, hydrocarbon source supply, combination type of hydrocarbon accumulation, and accumulation model. In addition, we briefly reviewed the progresses in oil-gas (including hydrate) exploration and development in the main offshore basins in China, provided some important references for further exploration and development of the remaining oil and gas resources in more-mature basins to guide more efficient oil-gas exploration and development in low-mature basins.