An eddy covariance observation was carried out in the upper reaches of the Shule River in 2009 for continuous measurements of CO₂ fluxes in alpine meadow ecological systems. Obvious daily and monthly variations in CO₂ flux were observed. For the daily variations in CO₂ fluxes in the growing season, the maximum influx postponed from 10:00 in May to 12:00 in July, and the maximum emission of the CO₂ flux occurred at 21:00-22:00. The maximum CO₂ uptake and emission rates were 0.93 g·m^-2·h^-1 and 0.41 g CO_2·m^-2·h^-1, respectively, both of which occurred in July. During non-growing season, the daily variation magnitude of the CO₂ flux was relatively small. Besides a small emission of CO₂ in the daytime, the flux in other time is very little. In a yearly cycle, April and October were the peaks of net CO₂ efflux, and from June to August was the net influx time, in which the net influx in July was the maximum. The total uptake by the ecosystem was up to 373.5 g CO_2·m^-2 in June through August. During the non\|growing season, the total amount of the net emission was 238.1 g CO_2·m^-2. Generally, the alpine meadow in the northeast Tibetan Plateau is typically a carbon sink, with an annual net uptake of 135.4 g CO_2·m^-2. However, the large daily range of air temperature is not necessary to enhance carbon gain in the northeast Tibetan Plateau.

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