Abstract: 【Objective】 Under the natural ecological conditions in Xinjiang, the effects of subsoiling depth on photosynthetic characteristics of the cotton canopy and yield were investigated to provide the theoretical basis for further clarifying the regulation effect of subsoiling on cotton yield. 【Methods】 The Xinluzhong No.88 variety was used as the experimental material and four treatments, no subsoiling (CK), subsoiling 30 cm (S₁), subsoiling 40 cm (S₂), and subsoiling 50 cm (S₃), were set up in the perennial tillage cotton field to examine the effects of different subsoiling depths on canopy structure, photosynthetic characteristics, dry matter accumulation and yield of cotton at key growth stages. 【Results】 The leaf area index and growth period of cotton showed a single peak curve, and the leaf area index reached the peak at the full flowering stage, where the leaf area index of subsoiling treatment increased by 0.92%-12.94% compared with CK.However, the trends of leaf inclination and the degree of canopy opening were opposite to that of the leaf area index, and the minimum value was found at the flowering stage.Compared with CK, the leaf inclination of subsoiling increased by 1.86%-5.29%, and the degree of canopy opening decreases by 32.7%-59.1%.The net photosynthetic rate at the early flowering stage increased with the depth of subsoiling, while the transpiration rate and stomatal conductance were the highest in S₂.The net photosynthetic rate, transpiration rate, and stomatal conductance at full flowering and full boll stage were the highest in S₂ and S₃, respectively, while there was no significant difference between S₂ and S₃ (P>0.05).Compared with CK, the initial stage of rapid accumulation of dry matter in subsoiling treatment was 1-3 days earlier than that in CK, and the duration was extended to 2-4 days.The maximum accumulation rate increased by 2.18%-18.01%, the boll weight increased by 3.58%-9.12%, and the seed cotton yield increased by 11.02%-21.93%, among which subsoiling 40 cm is the highest. 【Conclusion】 The combination of subsoiling with a depth of 40 cm(S₂) and conventional tillage can effectively improve cotton canopy structure, promote leaf photosynthesis, increase dry matter accumulation intensity of cotton, and increase seed cotton yield.