| The soil organic carbon is more active part in soil. It is important in soil productive forces and global carbon cycle that the dynamical condition of soil organic carbon. The content characters of soil organic carbon of alpine meadow in Eastern Qinghai-Tibetan Plateau were studied with field investigation and laboratorial analysis. The results indicated that the content of SOC in turn that took samples from three typical alpine Upland Shrub, Upland Meadow and Terrace Meadow we chose is US(67.49±0.83g.kg-1)> TM(67.16±1.02g.kg-1) > UM(63.42±0.65g.kg-1). The surface (0-20cm) SOC of UM and US had a descending trend from May to September, but SOC of TM had an increasing trend. The results also showed that the content and density of SOC in those three samples with a descending trend along the soil profile. The change of content of SOC in UM was from 36.99 to 64.49g.kg-1, in TM was from 39.41 to 72.32g.kg-1, and in US was from 35.14 to 76.24g.kg-1, the respective vertical coefficient of variation was 19.49%, 21.54% and 27.35%. The centent order of SOC at 0-10cm is US>TM>UM, the diversity among three did not reach to the significant level at 10-30cm, but the order is US-3,from 40.19 to 70.87kg.m-3and from 33.03 to 51.84kg.m-3, the respective vertical coefficient of variation was 12.80%, 20.55% and 15.61%. The density of SOC in US is always the lowest among UM, TM and US at 0-40cm, which showed that the storage of carbon in UM is larger than one in US in the same scale. Nature meadow has the large carbon pool capacity. The results showed that the storage of SOC was increased by moderate grazing. The available carbon of UM, US and TM all had a descending trend. The range of available carbon in UM changed from 8.19 to 17.41mg.g-1, in US from 8.66 to 17.62mg.g-1, and in TM from 9.63 to 17.68mg.g-1. The respective range of variation was UM(52.96%) > US(50.85%)>TM(45.53%). The change of the content of available carbon along soil profiles was no significant level . The maximum of carbon pool activity was not at surface layer, it was 0.395 at 10-15cm in UM, and it was 0.407 and 0.435 at 25-30cm in US and TM. The content of SOC in soil profiles was correlated with underground biomass, tatal nitrogen, available nitrogen, soil bulk density and pH. The effective factors on SOC were different in different samples, because of variation of vegetation and grazing action effect. The factors affecting the content of SOC at UM in turn were pH>soil bulk density>total nitrogen>underground biomass, at US the factors were total nitrogen>soil bulk density> available nitrogen> underground biomass, the factors at TM were available nitrogen> total nitrogen> underground biomass. The available carbon had a significant or most significant correlation to SOC, underground biomass ,total nitrogen, available nitrogen, soil bulk density and pH. The coherence was different in different points, the factors in UM were SOC> soil bulk density> pH> total nitrogen, at US the factors were SOC> available nitrogen> soil bulk density> total nitrogen> underground biomass, at TM the factors were SOC> available nitrogen.
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