Abstract: 【 Objective 】To reveal the physiological and ecological mechanism of the synergistic improvement of cotton plant row spacing configuration and defoliation ripening effect, reduce machine-picked impurities and improve the quality of raw cotton. 【 Methods 】Jinken 1643 was used as the experimental material, and the main row spacing configuration and defoliant in the northern Xinjiang cotton area were selected. The two-factor split-plot design was used in the project and the main area was the row spacing configuration, which was P₆: Wide-narrow row-spacing configuration, the row spacing configuration was 66 cm + 10 cm and P₃: Uniform row-spacing configuration, the row spacing configuration was 76 cm; the sub-area was sprayed with different defoliants, which were TR: Ruituolong (80% thidiazuron) and T : Xinthili (thidiazuron · ethephon suspension). By measuring the defoliation rate, miscellaneous leaf rate, boll dehydration rate, cotton boll opening rate and fiber quality of cotton plants under different treatment combinations, the effect of row spacing configuration on defoliation and ripening of cotton spraying different defoliants was discussed. 【 Results 】The main time period for the efficacy of the defoliant was 0-15 days after spraying the agent. The defoliation and boll opening effect of Xinthili on cotton was more rapid (0-10 d), and the defoliation rate and defoliation rate were high, the dehydration rate of cotton boll was high, and the net boll opening rate was high under the treatment of one film and six lines, which could rapidly promote defoliation and boll opening, but it would cause a significant increase in miscellaneous leaf rate and damage to the length of upper cotton boll fiber. However, under the treatment of one film and three lines, the effect of spraying Xinthili on defoliation and boll opening was poor. The defoliation and boll opening effect of Ruituolong on cotton was weak at the initial stage (0-5 d), and it mainly played a role after application (5-15 d). Although the defoliation rate and boll opening rate of cotton were slow under the treatment of one film and three lines, the final defoliation rate was not significantly different from other treatments, and it would not cause damage to cotton fiber length and increase of miscellaneous leaf rate. But the effect of spraying Ruituolong on defoliation and boll opening was poor under the treatment of one film and six lines. 【 Conclusion 】In summary, Xinseli has better and faster defoliation and boll opening under the configuration of one film and six rows, but it would cause the increase of raw cotton leaf impurities and the decrease of upper cotton boll fiber quality. Under the configuration of one film and three lines, the defoliation and boll opening effect of Ruituolong is relatively slow, but the final defoliation and boll opening effect is still high, and it would not cause the increase of leaf impurities and the decrease of fiber quality.