Abstract: Organic nitrogen is a crucial component of atmospheric nitrogen compounds, playing a significant role in the nitrogen cycle and marine ecosystems. This study utilized the third-generation air quality model WRF-CMAQ to estimate the dry deposition flux of atmospheric organic nitrogen over the China offshore regions during summer and winter in 2013 and 2017. We analyzed the spatiotemporal variations, quantified the impact of sea salt heterogeneous reactions on the deposition flux of atmospheric organic nitrogen to the ocean, and explored the changes in deposition flux characteristics during photochemical pollution events. The results indicate that the average dry deposition flux of atmospheric organic nitrogen over the China offshore regions in 2013 and 2017 ranged from 0.06 to 0.25 mg N/(m²·d). During summer, the deposition flux gradually decreased from north to south Bohai Sea: 0.15 mg N/(m²·d), Yellow Sea: 0.09 mg N/(m²·d), East China Sea: 0.06 mg N/(m²·d), while the opposite trend was observed during winter, with the highest flux in the East China Sea 0.22 mg N /(m²·d)/(m²·d)and the lowest in the Bohai Sea 0.05 mg N/(m²·d). From 2013 to 2017, the deposition flux of organic nitrogen increased in the Bohai Sea and the western coastal areas of the Yellow Sea (12%-17%), while decreasing in other areas (4% - 35%). During photochemical pollution events, the deposition flux of atmospheric organic nitrogen significantly increased (3.1-3.5 times). Sea salt surface heterogeneous reactions could enhance the deposition flux of organic nitrogen by 4.2-9.2 μg N/(m²·d)(10% - 40%) in certain regions, with a higher impact during winter than summer.