The seasonal variation, influening factors and source / sink of emission of greenhouse gases (CO2, N2O and CH4) from marsh, alder (Alnus Jeponica) swamp and birch (Betula platyphella) swamp soils were studied in Xiaoxingan Mountains of China during the growing season of using a static opaque chamber-GC technique. The results showed that: ①The average emission fluxes of CO2, CH4 and N2O from the marsh, Alnus Jeponica- swamp and Betula platyphella-swamp soils were 487.89, 382.27, 514.63 mg?m-2?h-1, 1.88, 1.03, 0.04 mg?m-2?h-1, 3.70, 58.61, 11.73 μg?m-2?h-1 in growing season respectively, The fluxes of CO2 were higher in summer, CH4 in summer and autumn, and N2O in spring and summer. ② Air temperature and soil temperature (≤ 20 cm) were the main factors affecting CO2 emission in the three wetlands soils; Soil temperatures (30-40cm) were the main factors affecting CH4 emission in the marsh soils;Water table and surface soil temperatures were the main affecting factors of CH4 emission in Alnus japonica swamp soil; Water table was the main affecting factors of N2O emission in the marsh soil; surface soil temperature was the main affecting factors of N2O emission in Betula platyphella swamp soil. ③During the growing season, All three wetland soils were the sources of CO2, CH4 and N2O (17.56, 13.76 and 18.53 t?hm-2?a-1; 67.54, 37.05 and 1.30 kg?hm-2?a-1; 0.13, 2.11and 0.42 kg?hm-2?a-1). their sources of CO2 were very similar (5.5%-21.6%); the soil of marsh was a strong source of CH4, the soil of Alnus japonica swamp was a medium source of CH4, the soil of Betula platyghella swamp was a weak source of CH4; and the soil of Alnus japonica swamp was a strong source of N2O, the soil of Betula platyghella swamp was a medium source of N2O, the soil of marsh was a weak source of N2O.