Abstract: 【Objective】 To precisely formulate cotton field moisture management system under equal row spacing and close planting and reveal the efficient production mechanism of machine-picked cotton. 【Method】 The cotton varieties Xinluzao 22 (P₂₂) with strong drought resistance (P₂₂) and Xinluzao 17 (P₁₇) with weak drought resistance were selected as the tested varieties, and in the machine-harvesting mode of equal row spacing, 3,000 (W₁), 3,900 (W₂) and 4,800 (W₃) m³/hm² treatment levels were set to measure and analyze the crop growth rate (CGR), net assimilation rate (NAR), cotton boll growth rate (BGR) and leaf area loading boll (LAB) under different treatments. 【Result】 With the increase of dripping water, cotton CGR, NAR, BGR and LAB all showed a significant upward trend.Among them, there was no significant difference between W₂ and W₃ treatments in the BGR from P₂₂ to the late blooming stage, but all were significantly lower than W₁ Treatment: The BGR of P₁₇ increased significantly with the increase of dripping water in each growth period.Among cultivars, the CGR, NAR, and LAB of P₂₂ were 12.8%-18.2%, 12.3%-12.9%, 10.3%-12.2% higher than P₁₇ from the full flowering stage to the late full boll stage, and the BGR was in the full bloom stage, full boll stage.In the later period, it was 11.9%-30.4% higher than P₁₇.Correlation analysis showed that the BGR in the late blooming period was significantly positively correlated with BGR and LAB in the blooming period, and CGR, NAR, and BGA in the blooming period were all significantly positively correlated. 【Conclusion】 Under the condition of equal row spacing and close planting, the selection of drought-resistant cotton varieties under the condition of 3,900 m³/hm² is beneficial to maintain a higher population growth rate and boll growth rate in the late stage of blooming to full boll, and promote photosynthetic production to cotton bolls.