By the method of static chamber-gas chromatography, this paper studied the nitrous oxide flux in three typical wetlands (perennial waterlogged Carex lasiocarpa marsh, seasonal waterlogged Deyeuzia angustifolia wet meadow, and perennially over-wet brushwood wetland) of Sanjiang Plain from 2002 to 2004. The results showed that the nitrous oxide flux in test wetlands presented obvious seasonal and annual variation, suggesting that these three typical wetlands were all the sources of atmosphere nitrous oxide during plant growth season, and the weak sink in winter. The annual average flux in C. lasiocarpa marsh, D. angustifolia and brushwood wetland was 53.928, 21.408 and 657.120 mg x m(-2) x yr(-1), respectively. No diurnal variation of nitrous oxide flux was observed in three typical wetlands, and there was no significant correlation between nitrous oxide flux and temperature.