A study has been undertaken to estimate fluxes of the greenhouse gases carbon dioxide (CO_2), methane (CH_4) and nitrous oxide (N_2O) in wetlands, to understand the effects of temperature factors on these processes and to estimate global warming potential (GWP). Using static chamber techniques, we measured CH_4, CO_2, and N_2O fluxes from four wetland types in Gansu Gahai Wetlands, China, from July 2011 to July 2012. The results showed high variations in CH_4, CO_2 and N_2O fluxes between the four wetlands, with the smallest values in the subalpine meadow (-0.0140.126 mg/m~2·h), marsh wetland (137.17284.51 mg/m~2·h) and mountain wetland (-0.0080.022 mg/m~2·h) respectively. The highest values of CH_4, CO_2 and N_2O fluxes were in marsh wetland (0.4980.682 mg/m~2·h), mountain wetland (497.81473.09 mg/m~2·h) and herbaceous peat (0.0940.117 mg/m~2·h) respectively. CH_4 and CO_2 fluxes varied seasonally. Maximal fluxes occurred between July-October 2011 and May-July 2012, then decreased and remained relatively steady, with some slight fluctuations during the winter and thawing or freezing periods. Further analysis showed that air temperature, soil temperature (at 5 cm), surface temperature and temperature inside the box were highly significantly positively correlated with CO_2 flux from the four wetlands. These variables were significantly positively correlated with CH_4 flux from mountain wetland but not from the other wetland types. They were significantly negatively correlated with N_2O flux from all four wetland types. The GWP estimates were 35.311, 13.520, 34.816 and 30.236 t CO_2/(hm~2 ·a) from herbaceous peat, marsh wetland, mountain wetland and subalpine meadow respectively. These results show that marsh wetland could significantly decrease the emission of greenhouse gases from the Gahai Wetlands.