Abstract: This study used the continuous online monitoring of gaseous element mercury (GEM) concentration data in the Yellow and Bohai Sea from December 9th to 19th 2019 to analyze the spatial distribution, source and influencing factors of GEM. The results showed that the average concentration of GEM was (1.92±0.69) ng/m³, and the variation range was 0.80～4.17 ng/m³. The spatial difference was obvious. The concentration of GEM in the Bohai Sea was higher than that in the Yellow Sea, but both the highest and lowest concentrations occurred in the southern sea area of the Shandong Peninsula. Affected by pollution event and high mercury emission in North China, the air mass carried the pollutants in North China, leading to an increase in the concentration of GEM offshore.The air masses from Siberia had lower GEM concentrations. High concentration of GEM was more likely to occur in westward wind. GEM concentration was significantly negatively correlated with wind speed (r=−0.217, P<0.01), and positively correlated with temperature (r=0.417, P<0.01). In winter, the concentration of GEM in the Yellow and Bohai Seas was mainly affected by onshore polluted air masses.