Nanpu Sag is a typical hydrocarbon-rich sag in Jidong Depression, Bohai Bay Basin. New discoveries have been made in several fields recently, showing great exploration potential of oil and gas in this sag. The conflict between the results of the 3rd resources evaluation and the current exploration practice is increasing evidently, which makes it difficult to guide the exploration. Through the analysis of petroleum geological characteristics of Nanpu Sag, this paper analyze the hydrocarbon accumulation conditions, establish hydrocarbon accumulation patterns in different exploration fields, and clarifies the regulations of hydrocarbon accumulation. Based on the assessment of the geological risks, the evaluation methods were optimized to carry out the calculation of resources, and to clarify the distribution of remaining resources and favorable exploration fields in the future. The results show that there are 12.20×108 t of the conventional oil resources, 2.19×108 t of unconventional oil resources, 7.1×108 t of remaining conventional oil resources. According to the principle of "considering both shallow and deep layers, exploring both oil and gas", it is pointed out that four structural zones, such as Gaoliu, Nanpu 1, Nanpu 2 and Laoyemiao, are the key exploration targets in the future.