A method, apparatus, and system for disaster recovery of an IP Multimedia Subsystem (IMS) are provided. The method includes: triggering a redundant Call Session Control Function (CSCF); obtaining, by the redundant CSCF, user backup data of registered IMS Private User Identities (IMPIs) that are associated with IMPUs and user service configuration data of IMS Public User Identities (IMPUs) in an IMS subscription from a network storage entity of a user; and recovering, by the redundant CSCF, a corresponding service according to the obtained user backup data of the registered IMPIs and user service configuration data of the IMPUs in the IMS subscription. With the present invention, the one-IMPU multi-IMPI, one-IMPI multi-IMPU, or multi-IMPI multi-IMPU service can be recovered, and this enables the user to have better service continuity experiences.