Abstract: Neonicotinoids have been widely used as an important class of insecticides for controlling sap-feeding insects. However, increasing application scope and duration have led to the development of neonicotinoid resistance, decreasing their efficacy. In this study, a series of biphenyl eight-membered oxabridge neonicotinoid analogues were developed based on our previous work. The synergistic activities of target compounds in combination with imidacloprid against the cowpea aphid (Aphis Craccivora) were evaluated, and the results showed that they could effectively enhance the insecticide activities of imidacloprid against A. Craccivora. Notably, compound D3 exhibited obvious synergistic action, causing a 4.04-fold increase in the insecticide activity of imidacloprid against A. Craccivora at a combination concentration of 1 mg/L. This work holds great significance for addressing the resistance issues faced by traditional neonicotinoids.