Carbon (CO₂ and CH₄) emission fluxes, annual net carbon sequestration of vegetation, were studied from seven kinds of natural wetlands (Carex schmidtii marsh-C, Betula ovalifolia-C. schmidtii shrub swamp-G, Alnus sibirica-C. schmidtii swamp-M, B. platyphylla-C. schmidtii swamp-B, Larix gmelinii-C. schmidtii swamp-L-T, L. gmelinii-moss swamp-L-X, and L. gmelinii-Sphagnum spp. swamp-L-N) in Xiaoxing'anling region of China using the static chamber gas chromatography method and the relative growth equation method to evaluate the carbon source or sink of natural forested wetlands based on net ecosystem carbon balance. The results showed that: 1) seasonal dynamics of CH₄ emission fluxes from seven kinds of natural wetlands could be divided into three types (single-peak, multi-peak, and emission and absorption alternating type) and CH₄ emission flux (0.006-7.756 mg m^-2 h^-1) exhibited a different trend in M (which was 1.0-1291.7 times greater than the others, P < 0.05) > C, G, B (17.7-649.0 times greater than L-T, L-X, and L-N; P > 0.05) > L-T, L-X, and L-N; 2)seasonal dynamics of CO₂ emission fluxes from the seven kinds of natural wetlands could be divided into two types (single-peak and double peak), and CO₂ emission flux (157.40-231.06 mg m^-2 h^-1) exhibited an different trend in G (which was greater 28.7%-46.8% than forested wetlands, P < 0.05) > C(7.4%-22.5% than forested wetlands, P > 0.05) > five kinds of forested wetlands; 3)CH₄ emission fluxes from C, G, M, B, and L-N were controlled by soil temperature, but that of L-T and L-X had no significant correlation with soil temperature at 0-40 cm. CO₂ emission fluxes from C, G, M, and L-T were controlled by air temperature and soil temperature, and that of B, L-X, and L-N were controlled by air temperature, soil temperature, and the water table level; 4) the annual net carbon sequestration of vegetation ((2.05±0.09)-(6.75±0.27) tC hm^-2 a^-1) had a different trend in C (greater than the others by 65.4%-229.3%,P < 0.05)> G, B, L-T, L-X, and L-N (greater than M by 80.0%-99.0%, P < 0.05) > M; and 5) the sources and sinks of carbon were significantly different among the seven kinds of natural wetland types (-2.32-2.09 tC hm^-2 a^-1). For example, C, B, and L-N exhibited varying degrees of carbon sinks, yet M, G, L-T, and L-X exhibited varying degrees of carbon sources. Therefore, marsh wetlands were greater carbon sinks and shrub wetlands were greater carbon sources, yet forested wetlands maintained overall carbon balance (except M) in the Xiaoxing'anling region of China.