Draining for forestation is one of the main disturbances of wetlands in Xiaoxing′an Mountains, Northeast China. To evaluate effects of wetland draining for forestation on methane emissions and affecting factors, methane fluxes in a natural Carex schmidtii marsh, a thicket swamp, 10- and 20- years-old Larix gmelinii plantations afforested after wetland draining were measured by using a static opaque chamber and gas chromatography method. Results showed that there was a significant seasonal pattern of methane fluxes in both wetlands and plantations, but the peak values in the latter were less than those in the former. Methane uptakes were observed in the plantations but not in the wetlands. The methane emissions in the plantations were significantly (10- years-old plantation: p=0.005; 20- years-old plantation: p=0.009) lower than those in the wetlands. Total methane emissions during growing season (150d) in the marsh, the swamp, the 10- and 20- years-old plantations were (6.66±8.31)g m-2 a-1, (0.32±0.31)g m-2 a-1, (0.13±0.50)g m-2 a-1, and (-0.11±0.20)g m-2 a-1, respectively. Water table lowering and vascular plants decreasing mainly contributed to the decrease of methane emission rates after wetlands draining for forestation. The decrease of draining ditches area may also cause methane emission rates decreasing in the plantations.