Oil is extremely crucial to the development of the modem economy.It is important to forecast the oil supply capacity due to its scarcity and non-renewability.This paper attempts to forecast and analyze thirty-five current and potential net oil-exporting countries.Integrating both qualitative and quantitative methods,the oil production and consumption are predicted based on historical data,so that the world net oil-exporting capacity can be obtained.The results show that the “roof effect” of the world net oil-exporting capacity may appear before 2030.Unconventional oil will play an important role in the future world oil market.The competition and cooperation relationships between OPEC and non-OPEC will last for a long time.