This review introduced the research progress of covalent modification strategies in local anesthetic drug delivery systems. As a commonly used and multimodal analgesic drug, local anesthetics have limited duration of action and potential toxicity in clinical application. In order to prolong the analgesic effect and reduce systemic toxicity, researchers are committed to the development of sustained-release local anesthetics with long-lasting dose-controlled-release functions. When it comes to the delivery of local anesthetics, the covalent modification strategy is a key approach. By covalently binding drugs to large molecule carriers, covalent modification strategies can improve drug stability, targeting and delivery efficiency. Macromolecular prodrugs can modulate the kinetic process of the drug, so that the drug is released in the form of the active ingredient and achieve better therapeutic effects. In recent years, stimulus-responsive macromolecular prodrugs have become a research hotpot for local anesthetic drug delivery systems, and the stimulus-responsive performance of macromolecular prodrugs can rapidly release drugs under internal and external stimulus conditions, and maintain low toxicity and high efficiency in blood circulation and normal tissues. These emerging research directions provide important guidance for prolonging the analgesic effect of local anesthetics and reducing systemic toxicity, and provide new idea for the development of more effective drug delivery systems in the future.