Studying the effects of film mulching on soil aggregate stability and soil organic carbon distribution in different aggregate fractions can provide a scientific basis for exploring proper practices to improve the productivity and protect the environment in dryland farming. A long-term field experiment has been conducted in Fuxin, Liaoning province since 2012. Three treatments were carried out:non-mulching (CK), autumn plastic film mulching (AP), and spring plastic film mulching (SP). The soil aggregate and soil organic carbon (SOC)contents of different aggregates (> 2, 0.25-2, 0.053-0.25, and < 0.053 mm)in 0-10 and 10-20 cm soil layers were measured using a wet sieving method. Our results showed that long-term plastic film mulching significantly affected the soil aggregate size distribution, aggregate stability, and organic carbon content in the 0-10 cm soil layer, especially under AP while there was no significant difference among treatments in the 10-20 cm soil layer. Compared to CK, the amounts of > 2 mm water-stable aggregates under AP and SP significantly increased by 36.3% and 26.7%, respectively. However, no obvious difference was observed in micro-aggregates. These results suggested that plastic film significantly affected the stability of soil aggregates and accumulation of aggregate into macro-aggregates. The mean weight diameter value of water-stable aggregate was significantly higher in AP and SP than in CK at 0-10 cm soil layer. Compared to CK, AP and SP significantly increased the total SOC contents and SOC in the aggregates > 2 mm in size at the 0-10 cm soil layer, increased by 8.2% and 47.9% as well as 4.6% and 29.2% (P < 0.05), respectively. The contribution rate of the > 2 mm aggregate in total SOC was obviously increased by 37% and 26.1% in AP and SP (P < 0.05), respectively. However, in the 0-10 and 10-20 cm soil layers, the SOC in the micro-aggregates (0.053-0.25, < 0.053 mm)did not significantly affect the contribution rate of total organic carbon. The results indicated that film mulching promoted the accumulation of aggregates into macro-aggregates. Under the soil and planting conditions in Liaoning, Autumn plastic film mulching can improve the stability of 0-10 cm soil water-stable aggregates and increase the SOC contents of macro-aggregates, as well as further promote the sequestration of organic carbon.