To evaluate the synergistic effects of organosilicon adjuvants on insecticides and improve the field control efficacy against the cotton aphid Aphis gossypii, the interfacial properties of Silwet819, Silwet806, Silwet820 and Silwet710 were determined. Their toxicities to cotton aphids and their synergistic ratios with sulfoxaflor and flonicamid were determined to identify the most effective adjuvants. Field trials were further conducted to evaluate their effects on reducing the application rate of flonicamid while maintaining efficacy. The results showed that among the four adjuvants, Silwet806 exhibited the strongest ability to reduce surface tension and increase maximum retention on leaf surfaces, while Silwet819 showed the greatest reduction in contact angle of leaves. All four adjuvants displayed certain insecticidal activity against cotton aphids and exhibited synergistic effects with both sulfoxaflor and flonicamid, with synergistic effects positively correlated with adjuvant concentration. At 0.05%, the synergistic ratios of Silwet819 and Silwet806 with sulfoxaflor were 5.12 and 6.71, respectively, and their synergistic ratios with flonicamid reached 12.80 and 6.40, respectively. Silwet806 and Silwet819 were identified as the most effective adjuvants, significantly enhancing the rapid efficacy of flonicamid against cotton aphids. When the application rate of flonicamid was reduced by 20% or 50%, the addition of 0.02% Silwet806 or Silwet819 achieved control efficacy comparable to the conventional dosage, while 0.05% addition resulted in higher control efficacy than the conventional treatment. These results indicate that Silwet806 and Silwet819 are optimal synergists for sulfoxaflor and flonicamid by modifying the physicochemical properties of spray solutions and reducing pesticide loss. In field control of cotton aphids, the addition of 0.02%-0.05% Silwet806 or Silwet819 can reduce flonicamid usage by 20%-50%.