Abstract: In order to explore the changes of soil nutrients after the reduction of chemical fertilizers in agricultural products and the impact of straw returning on soil fertility and carbon sequestration capacity, the quality and safety of agricultural products were strengthened. In this study, maize straw returning experiments were carried out in four pastures in Daqing City, Heilongjiang Province for three consecutive years starting from 2019, during which 31 sampling points were randomly selected for three sampling sessions to analyze the pH, alkali-hydrolyzable nitrogen, available phosphorus, available potassium, organic matter, organic carbon and water-soluble salts in soil samples. The results showed that the content of organic matter in the soil of long-term maize straw returning increased from 21.2 g·kg^-1 to 23.6 g·kg^-1. The average increase of available phosphorus content in straw returning soil was about 144%, while the average increase of available phosphorus content in unreturned soil was only about 138%. The alkaline hydrolyzable nitrogen content increased from 166.5 mg·kg^-1 to 194.5 mg·kg^-1, and there was a significant difference with the alkaline hydrolyzable nitrogen content measured in 2021. It can be seen that the soil carbon sequestration capacity and fertility increase after straw returning, and the pH has been maintained at 7.92-8.23. Therefore, the rational use of mazie straw returning to the field can improve the soil tillage environment, reduce the salt accumulation in the soil, improve the soil fixation effect on organic carbon, and adjust the acid-base stability of the soil, which is of great significance for the sustainable development of soil productivity in Northeast China.