Abstract: Northeast China is an important crop production area, so the amount of crop straw in northeast China is large. Among of main utilization approaches for straw, the straw returned to soil is the most widely adopted approach in China. Returning straw to the soil is beneficial for optimizing the soil environment, preventing and controlling soil degradation, and reducing air pollution that results from burning straw. Currently, straw is returned to the soil in the following three ways: mechanical crushing with backward pressure return, direct mulching and returning straw to deep soil layers. There are many problems with the first two approaches, straw decays slowly because it has a relatively high carbon-to-nitrogen (C/N) ratio, which is not beneficial for the next crop and can decrease the rate of crop emergence. Returning straw to deep soil layers, the bottom of the soil plow layer is broken, the soil bulk density is reduced, and the soil structure is improved. Meanwhile, as straw was buried in the furrow. Crops were planted on the ridge in next season. Thus, crop roots do not directly contact the straw, which could reduce the incidence of disease caused by the harmful substances produced during straw degradation. However, the optimal amount of straw return has not been determined yet. To determine the effects of straw application rates on the soil aggregate ,soil organic carbon content and maize yield under the condition of returning straw to deep soil layers, , The experiments were conducted in the experimental field of the agricultural technology popularization center of Lingyuan city, Liaoning province from 2011 to 2016. After corn harvest in October 2011, five treatments were tested: no straw application. The application of maize straw was at a rate of 6 000, 12 000, 18 000, 24 000 kg/hm2. The straw was incorporation into the subsurface of soil (>20-40 cm). Apply additional nitrogen fertilizer according to C:N=25.1 . The experimental plots were arranged using a random design with three replicates, and the area of each plot was 24 m2. The aggregates amount was examined by dry and wet sieving methods. After straw application for six years, compare with CK, all treatments significantly reduced soil bulk density. The size of dry-stable aggregate and water-stable aggregate were mainly >0.25 mm, <0.25 mm, respectively. Compared with CK, the straw application treatments increased mean weight diameter (MWD) and soil organic carbon content. With the increase of straw application rate, MWD increased. The effect on aggregate SOC of surface soil (0-20 cm) was greater than that of the subsurface soil (>20-40 cm). Compared with CK, the straw application treatments increased the maize yield during 2012－2016. In general, the maize yield increased the most was the straw application amount of 12 000 kg/hm2 among all treatments, so it is the recommended treatment. In conclusion, returning straw to deep soil layers can significantly improve aggregate SOC, soil structure, stability and maize yield and is a suitable agricultural practice to improve soil quality in Northeast China.