Abstract:As an important indicator for soil structure, soil aggregates have a huge impact on soil porosity and water holding capacity. Soil aggregate organic carbon can not only reflect soil carbon sequestration capacity, but also be closely related to aggregate stability. Study on soil aggregates and organic carbon distribution characteristics in Chinese Fir plantations can provide theoretical basis for improving soil productivity and water use efficiency. In our research, soil samples were collected from Chinese Fir plantations with different forest ages (6, 11 and 32 years), which was located in Yangkou National Forest Farm, Fujian Province, China. The water-stable soil aggregate composition and organic carbon contents were measured. The results showed that forest age was very important in terms of soil aggregate and its organic carbon. Macro-aggregate contents (>0.25 mm), MWD, organic carbon contents and its contribution of aggregates in mature forest were higher than that in young and middle forests. Water-stable macro-aggregates were the main part of soil aggregates, which accounting for about 59.57%~80.97%, while the aggregates with the partical size less than 0.053 mm only accounted for 0.80%. In terms of organic carbon contribution, macro-aggregates were the main contributor, and aggregates with the partical size 2~0.25 mm accounted for 58.43%. Furthermore, soil aggregate MWD and its carbon content had a typically vertical characteristic, decreasing with soil depth. A strong positive correction was found between aggregate MWD and organic carbon. Hence, organic carbon was beneficial for the stability of soil aggregate, and MWD and organic carbon contents of aggregate showed a trend as mature forest > young forest > middle forest.