Abstract: 【Objective】 The changing rule of agronomic characters, canopy structure, light distribution, and yield topping-free cotton based on regulation of DPC, which provide the basis for light and simplified cotton cultivation. 【Methods】 The varieties Xinluzao 67(P₁), Z901(P₂), Z903(P₃) and which relatively sensitive to mepiquat chloride were used as experiment material, the topping-free method DPC replace manual topping, manual topping as control (Xinluzao 60, CK) the agronomic characters, canopy structure, light transmittance, dry matter accumulation and distribution, yield and other indicators. 【Results】 The results showed that compared with manual topping, the plant height, the number of sympodials and the leaf age of topping-free cotton were increased significantly. them, the increasing range of P₂ plant height and the number of sympodials w, 45.2% and 100% respectively, and the increasing range of P₃ leaf age was larger, 39.4%. P₁ had the largest leaf area index, P₂ had the smallest decreasing amplitude after reaching the peak value, only 19.6%, P₁ had the smallest DIFN valley value, P₃ had the smallest increasing range after reaching the valley value, P₂ had the greatest MTA peak value which 3.4% taller than CK, while P₃ was smallest which only 0.9% taller than CK. The light transmittance of each part of the canopy showed an increasing trend in the later period of growth, among, P₄ upper canopy layer light transmittance had the largest increasing range which reached 27.1%, P₃ had the smallest increasing range which only 10.7% oppositely, P₂ middle canopy layer light transmittance increasing range was largest, 28.3%, P₄ had the smallest increasing range which only 14.6%, P₃ lower canopy layer light transmittance was largest, 23.9%, P₄ had the smallest increasing range which only 4.0%. The proportion of dry matter quality of reproductive organs to that of vegetative organs of P₃ was largest, 2.2∶1, P₁ 2.1∶1owever the cumulative increase in total dry matter mass per plant was the largest, at 81.9 g/plant. Compared with CK, the yield of P₁ and P₃ were not significantly. 【Conclusion】 The cotton varieties Xinluzao 67 and Z903, which are sensitive to mepiquat chloride, were sprayed with DPC (45+30+30+30+120+150) g/hm² before emergence, two leaves and one heart, before head water, before two water, July 5 and July 12, respectively, full-process DPC control instead of manual detopping, on the basis of not significantly reducing cotton yield which can reduce production costs by 46% and increase cotton planting benefits.