N₂O is one of the more important greenhouse gases and ozone-depleting substance with the largest emission rate.  The ocean is among the more important N₂O sources to the atmosphere and accounts ~21% of the global N₂O. However, the roles that Polar Oceans play are not well known due to paucity of N₂O data at  these regions. An autmoatic underway system for N₂O measurement was developed and applied onboard research vessel during the past several years in both Chinese Arctic, Antarctic and MOSAiC Expedition. In these studies, the underway system provided high resolution and precision data that reveal the fine structure of N₂O distribution along the cruise tracks in the polar oceans, together with other underway parmeters, indicating regulation factors on the N2O distribution. The high resolution characteristics of data set obtained using this system also contributes to better evaluation of  air sea N₂O flux of polar ocean and other oceans as well.