The cycling stability of SnO₂ anode as lithium-ion battery is poor due to volume expansion. Polyimide coatings can effectively confine the expansion of SnO₂. However, linear polyimides are easily dissolved in ester electrolytes and their carbonyls is not fully utilized during charging/discharging process. Herein, the SnO₂ enclosed with anthraquinone-based polyimide/reduced graphene oxide composite was prepared by self-assembly. Carbonyls from the anthraquinone unit provide fully available active sites to react with Li⁺, improving the utilization of carbonyl in the polyimide. More exposed carbonyl active sites promote the conversion of Sn to SnO₂ with electrode gradual activation, leading to an increase in reversible capacity during the charge/discharge cycle. In addition, the introduction of reduced graphene oxide cannot only improve the stability of polyimide in the electrolyte, but also build fast ion and electron transport channels for composite electrodes. Due to the multiple effects of anthraquinone-based polyimide and the synergistic effect of reducing graphene oxide, the composite anode exhibits a maximum reversible capacity of 1266 mAh·g⁻¹ at 0.25 A·g⁻¹, and maintains an excellent specific capacity of 983 mAh·g⁻¹ after 200 cycles. This work provides a new strategy for the synergistic modification of SnO₂.