This study compiled data on the ^239+240Pu concentration or specific ratio-activity, ²⁴⁰Pu/²³⁹Pu atom ratio, and ^239+240Pu flux or inventory in seawater, corals, shells and sediment samples in the northern South China Sea. The ^239+240Pu sources and trends in surface seawater, water columns, surface sediments, and sediment cores in this area were presented. According to the two end member model, global fallout (GF) and the Pacific Proving Grounds (PPG) were currently the sources of ^239+240Pu in environmental samples investigated from the northern South China Sea. Meanwhile, according to the migration model, it was found for the first time that a positive linear relationship between the water depth corresponding to the ^239+240Pu peak concentration in the water column and its migration rate. The correlation between the organic matter content or particle size of surface sediments and the ^239+240Pu specific ratio-activity had a segmented nature, showing positive and negative correlations, respectively. The numerical result of the ^239+240Pu chrono-marker sedimentation rate in sediment core samples was usually greater than or equal to the maximum apparent diffusion rate of relatively exchangeable ^239+240Pu in the same core sample, and there was a significant positive linear relationship between the sedimentation rate and the maximum apparent diffusion rate, the impact of the maximum apparent diffusion rate of relatively exchangeable ^239+240Pu in the core sample on the sedimentation rate can be ignored.