This application relates to the field of battery technologies, and discloses a method for updating an OCV-SOC curve of a battery pack, a battery management system, and a vehicle. The method for updating an OCV-SOC curve of a battery pack includes: obtaining information that represents an aging state of the battery pack; obtaining a current aging characteristic parameter of the battery pack based on a current OCV-SOC curve of the battery pack and the information; and updating the OCV-SOC curve of the battery pack based on the current aging characteristic parameter and the current OCV-SOC curve of the battery pack. In this application, the OCV-SOC curve of the battery pack is updated based on the aging state of the battery pack, thereby obtaining an OCV-SOC curve that meets the aging state of the battery pack and making it convenient to estimate the online state of the battery pack more accurately.