The invention relates to a polymeric ionic liquid modified reduced graphene oxide loaded doxorubicin, as well as a preparation method and an application of the polymeric ionic liquid modified reduced graphene oxide loaded doxorubicin. The preparation method of the polymeric ionic liquid modified reduced graphene oxide loaded doxorubicin comprises the following steps: preparing PIL-RGO (Polymeric Ionic Liquid-Reduced Graphene Oxide); dissolving a PIL-RGO composite into water, adding a doxorubicin hydrochloride aqueous solution, adjusting the PH to neutral, stirring for a reaction under the shading condition, centrifuging to remove DOX not loaded, and freeze-drying to form the PIL-RGO composite. The carrier material is excellent in solubleness in water, and the stability is strengthened. The polymeric ionic liquid modified reduced graphene oxide loaded doxorubicin has the PH sensitive release characteristic after being loaded, the detention time of DOX in the body is prolonged, and the sustained-release effect is achieved, so that the treatment effect is strengthened. The polymeric ionic liquid modified reduced graphene oxide loaded doxorubicin can be applied to the studies on antitumor, and has excellent clinical study and application values.