Disclosed in the present disclosure is a biodegradable amphiphilic polymer containing disulfide in the side chain, a self-crosslinked polymeric vesicle thereof and an application in the targeted therapy of lung cancer. The polymer is obtained by an activity-controllable ring-opening polymerization based on a cyclic carbonate monomer containing a functional group of dithiolane ring, which has a controllable molecular weight and a narrow molecular weight distribution, and does not require processes of protection and deprotection; the polymer obtained by the ring-opening polymerization of the cyclic carbonate monomer of the present disclosure has biodegradability and can be used to control the drug release system, the prepared lung cancer-targeted reduction-sensitive reversibly-crosslinked polymeric vesicle as a nanomedicine carrier supports stable long circulation in vivo. However, it is highly enriched in lung cancer tissues, enter cells efficiently, and rapidly decrosslinks in the cells to release drugs, so as to kill cancer cells with high potency and specificity and inhibit the growth of tumor effectively without causing toxic and side effects.