After sowing winter wheat from 2018 to 2020， the cotton stalk was mechanically crushed and covered before returning to the field to study the decomposition dynamics of cotton stalk returning to the field and the impact of different amounts of cotton stalk returning to the field on the yield of wheat. Three treatments including zero stalk returning （ZS）， half stalk returning （HS） and all stalk returning （AS） were set up with the randomized block. The decomposition， nutrient release， and structural component changes of cotton straw with different returning amounts were analyzed. The results showed that the decomposition rate of straw was first fast and then slow， with the fastest decomposition occurring 20 days after returning to the field， and then gradually decreasing. After 170 days of returning to the field， the decomposition rates of HS and AS were 73.4% and 66.8% respectively from 2018 to 2019， and 77.6% and 60.4% respectively from 2019 to 2020. There were differences in the release rates of different structural components in straw. After 170 days of decomposition， the release rate of soluble sugars in cotton culms was 70.7%-81.38%， followed by cellulose （57.3%-60.7%） and lignin （44.1%-50.3%）. There were also differences in the release rates of N， P， and K in cotton stalk， with K release rates ranging from 83.1% to 87.9%， P release rates ranging from 71.4% to 80.5%， and N release rates ranging from 66.5% to 74.7%. Returning cotton stalk to the field increased the number of spikes per unit area of wheat， thereby increasing the yield of wheat. It is indicated that returning cotton stalk to the field is beneficial for improving soil nutrient status and increasing the yield of winter crop （wheat）， with all stalk returning （AS） being better.