| Mankind processed vegetation restoration and optimized soil resources according to the theory of systems engineering and ecology-economics in Ning-nan the hilly area of Loess Plateau of China, which not only controlled the loss of soil and water and improved environment, but also increased income and soil productivity. Vegetation is not only the factor that influences soil development, but one of way to improve soil the ability to resisting erodes. We determined the soil organic carbon,distribution of soil aggregate,active organic carbon and the pool of organic carbon under different vegetation and ages in Shang huang and Wang wa in Ning nan. We provided the hierarchical stability of soil aggregate and account the carbon pool of the management index to indicate the benefits of soil environment after vegetation restoration. The aim of this article was studying the relation between the stability of soil aggregate and the pool the carbon, which may be gained from two factors, one was to know the reason of stability of soil aggregate and its appraising, the other was to study the effects of vegetation restoration on the pool of carbon. The results obtained were summarized as follows: 1. The kind of vegetation effect soil organic matter and nitrogen, the amount of organic carbon in savageness grassland is higher than man build, Hippophae rhamnoides higher than caragana korshinskii. The ratio of C/N in soil under different vegetation can indicated the turnover of carbon from vegetation. The amount of organic carbon in aggregate centralized >0.5mm diameter which showed vegetation increase the amount of organic carbon of big aggregate. The ages of restoration can increased organic carbon in soil and aggregates, growth environments influence soil organic carbon in aggregate. 2. The fractal fraction under waste　slope was lowest and it under cropland was highest, vegetation restoration decreased the fractal fraction of aggregate. The MWD under soil of Caragana Microphylla was bigger than that of under other vegetation. There was a negative correlation between the fractal fraction and the amount of >0.25mm aggregate。On the contrary there was a correctitude correlation between MWD and amount of <0.25mm aggregate。We appraised the stability of aggregate and impact of vegetation restoration based on hierarchical of stability of aggregate in Zi Wu-ling. 3. We studied the relationship between stability of soil aggregate and organic carbon applied mean weight diameter, the result indicate that there was no significance relation between stability of soil aggregate and mean weight diameter, and there was power function between the content of organic carbon and ratio of fractal dimension and organic carbon, which relation consist in every aggregate (>0.25mm). 4. Vegetation increased the carbon pool of management index (CMPI) that was a sensitivity index to soil management; CMPI under cropland was lower than that under other vegetation. The CMPI in >0.25mm aggregates were highest, the CMPI in 0.5-1.0mm aggregates was lowest, all of CMPI in aggregate increased after vegetation restoration. 5. Vegetation restoration increased soil organic carbon and no-active organic carbon, The organic carbon and no-active organic carbon under the soil of grass was highest during 0-30cm horizon, the stable organic carbon under the cropland was lowest, so vegetation restoration increased carbon sequestration in soil, strengthen the soil as the sequestration, the ability of deposited stability carbon under grass land>Prunus armeniaca var.ansu>Hippophae rhamnoides L>Caragana microphylla.
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