In order to explore the optimum additive formula that promotes straw decomposition and soil carbon sequestration, the effects of additives on the straw decomposition and its surrounding soil environment were studied. We chose corn stalks as test materials to carry out the burial bag in-situ decomposition experiment for 150 days. The effects of three types of additives (urea, biological bacteria decomposition accelerator and trace element conditioner) on the decomposing process of 15 cm and 30 cm depth returning straw and the soil environmental factors were studied. The results showed that:(1) Additives significantly affected the amount of carbon loss (p<0.01), directly affecting the degree of straw decomposing and the release of carbon in the soil. The depth of returning to the field affected the weight loss by affecting the water content, and the water content was significantly negatively correlated with the weight loss (r=-0.51). SOC and carbon loss were close to a linear negative correlation (r=-0.94), and SOC was significantly positively correlated with C/N (r=0.72), and C/N was significantly negatively correlated with carbon loss (r=-0.53). (2) The trace element additive not only improved soil water content in the early stage, but also slowed the loss of water in the later stage. However, the additive had the tendency to accelerate soil acidification. The effect of trace element additive was more obvious at the depth of 15 cm, but the biological additive worked better at 30 cm depth. (3) The additives accelerated the decomposition of the straw but reduced the carbon loss. After 150 days, the average carbon loss of 15 cm and 30 cm depth returning to the field were reduced by 3.4% and 4.8%, respectively, which was conducive to soil carbon sequestration. Among them, the biological bacteria additive was more conducive to the decomposing of 15 cm returning straw, and the nitrogen additive was more conducive to the decomposing of 30 cm depth returning straw. (4) The additives slowed down the loss of the straw decomposing products, especially the biological bacteria additives and trace element. When the 15 cm depth returning field was used, the biological bacteria additive was more conducive to soil carbon sequestration, and the trace element additive was more conducive to the renewal of organic carbon, while the 30 cm depth returning was the opposite.