During the 22nd Chinese Antarctic Research Expedition (CHINARE-22), the atmospheric gas samples above the oceanic surface and near the surface were collected on the track for the scientific ship "Xuelong" and on Millor Peninsula of eastern Antarctica, respectively, using the Tedlar gas bags. Every day the sampling times were 10:00 and 22:00 (local time), respectively. In the laboratory, high-precision measurement of the isotopic compositions for N 2 O in these gas samples was conducted using Thermo Finnigan MAT-253 Isotopic Mass Spectrometer with a fully automated interface for the pre-GC concentration (PreCon) of trace gases. The temporal and spatial variations of G 15 N and G 18 O in atmospheric N 2 O were analyzed. The mean G 15 N and G 18 O-N 2 O values above the oceanic surface were (7.21±0.50)‰ and (44.52±0.52)‰, respectively. From 30°N to Antarctica, the G 15 N (6.05‰ 7.88‰) linearly increased with the rate of about 0.01‰ with the latitude while the G 18 O (43.05‰ 48.78‰) showed a large fluctuation. The G 15 N negatively correlated with air temperature and N 2 O concentration, and slightly positively correlated with G 18 O. The summertime variations of G 15 N and G 18 O-N 2 O appeared the same trend on Millor Peninsula of eastern Antarctica. They significantly positively correlated with each other and negatively with N 2 O concentration. The G 15 N and G 18 O-N 2 O at different sites averaged (7.42±0.35)‰ and (44.69±0.49)‰, respectively, slightly higher than those above the oceanic surface, significantly higher than those of atmospheric N 2 O in the low-latitude regions of Northern Hemisphere. The predominant factors affecting the spatial variations of G 15 N and G 18 O values were also discussed. The isotopic data given in this study can help to investigate the global and regional N 2 O budgets. nitrous oxide, Antarctica, atmosphere, G 15 N, G 18 O, isotope, ocean Nitrous oxide (N 2 O) is one of important greenhouse gases and its atmospheric concentrations have risen from about 270 ppb during the pre-industrial era to 319 ppb in 2005 [1] . The global sources of atmospheric N 2 O are categorized into anthropogenic and natural sources. Anthropogenic sources include fossil fuel combustion and industrial processes, agriculture, biomass and biofuel burning, human excreta, rivers, estuaries, coastal zones and atmospheric deposition; natural sources include soils under natural vegetation, oceans and atmospheric chemistry. Of all the sources the N 2 O emissions from the soils (including agricultural and natural soils) and the aquatic systems (including oceans, rivers, estuaries and coastal zones) account for about 53% and 31%, respectively. The emissions from other sources only account for about 16% [1] . Therefore the soils and aquatic systems are the main sources for atmospheric N 2 O [1] . The only significant sink is destruction in the stratosphere by UV