Abstract: In order to promote soil carbon sequestration and maize yield increase in the semi-arid region of western Heilongjiang Province, the long-term positioning experimental field of cultivation and straw at the Heilongjiang Academy of Agricultural Sciences was taken as the research object. The effects of CK（conventional planting）, NFG（straw mulching and returning）, and SFG（deep loosening+straw mulching and returning） treatments on soil organic carbon, different particle size organic carbon, water-soluble organic carbon content, and yield were analyzed, Study the effects of deep loosening and straw mulching on soil carbon composition and maize yield in semi-arid areas. The results indicate that:（1） The order of soil organic carbon and water-soluble organic carbon content in the 0-10 cm and 10-20 cm soil layers is SFG＞NFG＞CK.（2） In this experiment, the organic carbon content of clay particles（＜0.053 mm） was significantly higher than that of sand particles（＞0.250 mm） and silt particles（0.053-0.250 mm）.（3）In the 0-10 cm soil layer, the organic carbon content of sand particles（＞0.250 mm）, clay particles（＜0.053 mm）, and silt particles（0.053-0.250 mm） treated with SFG and NFG increased by more than 10% compared to the control CK. In the 10-20 cm soil layer, the organic carbon content of SFG treated sand particles（＞0.250 mm） and NFG treated powder particles（0.053-0.250 mm） increased significantly.（4） There was no significant difference in maize ear length, ear diameter, and ear row number among different treatments. The difference in grain number and yield per spike reached a significant level. Among them, SFG and NFG treatments increased the yield by 28.57% and 15.10% respectively compared to CK. There is a highly significant（P＜0.01） positive correlation between yield and soil organic carbon content, and a significant（P＜0.05） positive correlation with organic carbon and water-soluble organic carbon content of different particle sizes.