Soil aggregates are organic-inorganic complexes and the basic unit of soil structure. Their formation and stability are closely related to soil organic carbon content. The distribution of aggregate-associated organic carbon determines the capacity for soil organic carbon storage and retention. Currently, research on soil aggregate-associated organic carbon mainly focuses on agricultural and artificial ecosystems; relatively few studies have focused on natural ecosystems. In particular, little is known about distribution of aggregate-associated organic carbon in halophyte communities in Xinjiang. In light of this, a field experiment was conducted on an alluvial fan in the Manasi River Basin to quantify changes in soil aggregation and aggregated-associated soil organic carbon associated with four halophytes (Karelinia caspia, Bassia dasyphylla, Haloxylon ammodendron, and Tamarix ramosissima). Our objective was to determine 1) the particle size that is most conducive to carbon retention and 2) which of the four halophytes is associated with the accumulation of the most soil organic carbon. The results showed: 1) 46.7% to 74.6% of the total soil mass comprised particles of intermediate diameter (0.25-0.053 mm). This was significantly greater (P < 0.05) than the other two classes of particle size defined in this study ( > 0.25 mm and < 0.053 mm). The > 0.25 mm or < 0.053 mm classes only comprised 7.8% to 43% of soil mass. The > 0.25 mm class was most abundant in the Haloxylon ammodendron community, accounting for 32% of soil mass. 2) Soil total organic carbon content was 2.01-8.73 g/kg, and aggregate-associated soil organic carbon content varied from 1.70 to 13.68 g/kg among communities. Total organic carbon and aggregate-associated organic carbon were greater in the Haloxylon ammodendron and Tamarix ramosissima communities than in the other communities studied. These measures decreased in all communities with depth. 3) The aggregate-associated organic carbon content was lowest in the 0.25-0.053 mm class, and significantly higher (P < 0.05) in the >0.25 mm and < 0.053 mm classes. 4) Because the 0.25-0.053 mm class was the most abundant, aggregate-associated organic carbon in this fraction contributed more to soil total organic carbon contained 43.43%. There was more aggregate-associated organic carbon in the < 0.053 mm class, but this contributed less to total soil organic carbon, indicating that these micro-aggregates have the greatest potential to retain soil organic carbon. There was a significant negative relationship between the abundance of 0.25-0.053 mm soil aggregate particles and soil organic carbon content.Total soil organic carbon, aggregate-associated soil organic carbon and abundance of >0.25 mm aggregate particles were highest in the Haloxylon ammodendron community, which implies that this community has the greatest potential to gather soil nutrients of the four communities studies, could be useful for accumulating soil organic carbon in arid areas.