【Objective】 The objective of this study was to explore the organic carbon changes of soil and aggregate, to reveal the quantitative relationship between organic carbon stocks and additional organic carbon input, and to clarify the carbon fixation effect of soil and aggregates, and the mechanism of quantitative enhancement for organic carbon.【Method】 The field fixed experiment about straw returning amount was set up in the main corn production area of Nong'an County, Jilin Province in April 2012. The treatments included four different corn straw returning amounts of 0 (SA₀), 4 500 (SA₃₀₀), 9 000 (SA₆₀₀), and 13 500 kg·hm ^-2 (SA₉₀₀). The record information related to soil organic carbon (SOC) stocks and additional organic carbon input during the 7 years were used to analyze the quantitative relationship and carbon sequestration efficiency. Soil samples were separated into ＞2 mm, 2-0.25 mm, 0.25-0.053 mm, and ＜0.053 mm by using the wet sieving method in order to analyze the organic carbon of aggregates and carbon fixation effect. 【Result】 The results showed corn straw returning could significantly increase SOC content, the SOC under SA₉₀₀ and SA₆₀₀ were significantly larger than that under SA_O and SA₃₀₀, There were significant differences in soil organic carbon content between SA₉₀₀ and SA₆₀₀ treatments in the last three years. Compared with SA₀ treatment, from 2015 to 2018, SA₉₀₀ increased soil organic carbon by 11.0%, 15.8%, 17.2% and 23.1%, respectively. Significantly positive linear correlation was observed between the SOC stocks and additional organic carbon input (P＜0.01), and the sequestration efficiency of total organic carbon was 12.9%. Compared with SA₀ treatment, SA₆₀₀ and SA₉₀₀ treatments significantly increased organic carbon contents of aggregates (P＜0.05), especially in the macroaggregates; the organic carbon storage of SA₉₀₀ treatment increased by 45.5% and 47.7% in the ＞2 mm and 2-0.25 mm of aggregates, respectively. Except for ＜0.053 mm aggregate, there was a significant positive linear correlation between the increase of organic carbon storage and cumulative carbon input in other particle aggregates. The carbon sequestration efficiency (CSE) of larger size aggregates was significantly higher than that of smaller size aggregates, and ＞2 mm and 2-0.25 mm size aggregates were 4.9% and 13.6%, respectively. According to the soil carbon sequestration efficiency, the soil organic carbon storage should be increased by 10%, 20% and 30% in the next 10 years, and about 5.99, 11.98 and 17.97 t·hm ^-2 of air-dried corn straw should be added each year, respectively.【Conclusion】Corn straw returning could significantly promote the accumulation of organic carbon in soil and aggregates of Chernozem. The content of soil organic carbon increased with the increase of the amount of straw returning and the experimental years, while the organic carbon sequestration was mainly distributed in the macroaggregates. The results showed that straw returning to field was an important fertilization to improve soil fertility in black soil area, and the macroaggregate organic carbon could be used as an important index to evaluate the rapid response of soil organic carbon to different soil fertility measures