Physical fractionation and chemical analysis were conducted of upland red soils different in fertilization combination to study variation of organic carbon fractions in aggregates >2000,250～2000,53～250 and <53μm in particle size.Results show that long-term combined application of organic manure and inorganic fertilizer could significantly increase content of total organic carbon in soil (TOC) and content of organic carbon in light fraction (LF-C),coarse fraction (CF-C),inside particle organic carbon-fine (FF-C) and mineral-associated organic carbon (mSOC) in aggregates of all sizes.And organic carbon contents in various fractions of aggregates were significantly related to TOC.Content of organic carbon in aggregates decreased with the decreasing particle size of aggregates.Application of livestock manure significantly improved SOC content,dominated with mineral-associated organic carbon.Application of organic manure reduced turnover rate of macro-aggregates,and incorporation of crop residues contributed more than application of organic manure to formation and stability of aggregates.In the red soil region,the effect of long-term combined application of organic manure and inorganic fertilizer on formation and stability of aggregates should be intensified.