Abstract: The data of ^239+240Pu sediment cores in Bohai and Yellow Seas were collected, the source, vertical distributions and inventories of ^239+240Pu were comprehensively studied, and the absolute values of ^239+240Pu in sediments of Bohai Bay and South Yellow Sea were also estimated. The results showed that ^239+240Pu in the Bohai Sea and Yellow Sea mainly come from global fallout (GF) and Pacific Proving Grounds (PPG) close-in fallout. There are three ^239+240Pu distribution types in sediment cores: double peaks, single peak and no peak, respectively. Two types of ²⁴⁰Pu/²³⁹Pu in sediment cores, which were stable and unstable (single cycle and multi-cycle), respectively. The average ^239+240Pu inventory in Bohai Sea (Bay) was higher than that in South Yellow Sea, that means the Bohai Bay was a siltation type sea area. This study also provides a reference for the future studying of the vertical distributions of ^239+240Pu and the source of pollutants in sediment cores of the Bohai and the Yellow Seas.