The Qinnan Sag in the Bohai Bay Basin is lowly explored, where hydrocarbon generation potential of source rocks is required detailed investigation to identify hydrocarbon exploration potential and exploration targets. Methods: Burial history, thermal history, and hydrocarbon generation history of source rocks at various subsags were reconstructed on BasinMod software based on reasonable geological model and parameters derived from geological analogy. Results:Source rocks in the Eastern Subsag were mature at early stage due to differential subsidence and sedimentation, which was lasted for a long period and was currently at maturity to high maturity stage (Ro=1.0%～2.0%). Two hydrocarbon generation events were occurred to them in the Oligocene and Miocene, respectively, with intensive hydrocarbon generation capacity. Source rocks at the Southeastern Subsag were mature at later stage, which was lasted for a short period and was currently at medium maturity stage (Ro=0.7%～1.0%). Hydrocarbon generation was primarily occurred since the late Miocene, with intensive hydrocarbon generation capacity. Source rocks at the Western Subsag were generally at low maturity stage (Ro＜0.7%), which began to generate hydrocarbon since Pliocene, with weak hydrocarbon generation capacity. The hydrocarbon generation capacity of source rocks is generally in an order: Es3>Es1>Ed3. Conclusions: The Qinnan Sag has high oil and gas exploration potential, where exploration activities should focus on effective traps located in the dominant migration direction of the depression and slope zones in the Eastern and Southeastern Subsags.