Physical protection of aggregates is one of the important mechanisms of soil organic carbon(SOC)stabilization，and the formation of aggregates also depends on soil organic carbon.Through 31 years of long-term field experiments，the effects of different nutrient management measures on SOC and aggregate stability were studied，the distribution of bound carbon in soil aggregates was ascertained，and the physical protection mechanism of soil aggregates on SOC was explored，which could provide a basis for the optimal management of farmland SOC in the arid region of Northwest China.Soil samples from a long-term experiment with six different fertilization measures were collected，soil aggregate components and aggregate bound organic carbon were separated and determined by wet sieving method，soil total organic carbon，aggregate distribution and aggregate combined organic carbon were analyzed，and the stability of soil aggregates and the turnover of large agglomerations were evaluated.Results showed that the SOC content of manure amendment treatment could up to 39.7 g·kg-1，which was 1.8 and 1.4 times higher than those of no-fertilization and straw-returned treatments，respectively.The manure amendment treatment and straw-returned treatment could significantly increase SOC，while fertilization alone or abandoned soil could only maintain the balance of soil organic carbon.In addition，the manure amendment and straw-returned treatments increased the soil macroaggregation by 246% and 147%，respectively.Moreover，the turnover of the macroaggregation of manure amendment and straw-returned treatments were 33% and 53% of no-fertilization，which were significantly slower(P<0.05) than that of no-fertilization treatment.At the same time，the organic carbon bound by the agglomerate was transformed into a relatively stable fine-particle organic carbon，which was more conducive to the fixation of the organic carbon. Applying chemical fertilizer alone or abandoned soil organic carbon could maintain the input and output balance of SOC，the proportion of soil large aggregates and the stability of aggregates were significantly improved compared with no fertilizer，and the turnover rate of large aggregates was significantly slowed down.When the SOC content was low，the organic carbon content of silty clay particles dominated，and when the soil was rich in organic carbon，the fine particle organic carbon content dominated.All in all，the results showed that the application of organic fertilizer could not only make up for the decline of macroaggregates caused by tillage，but also promote the formation of soil aggregates，and the stability of soil aggregates could also be enhanced.The new SOC was first combined with macroaggregates，then fine particulate organic carbon was mainly used for fixation，which was better than straw returning.Long-term application of chemical fertilizer alone was difficult to improve SOC； the SOC encapsulated in microaggregates and fine particles in macroaggregates are relatively stable.Abandoning wasteland can reduce the physical damage to the soil and promote the accumulation of large aggregates.