A subscriber identity management method, a device, and a system. The method includes: a network device that receives a first message from a terminal device, where the first message includes a first subscriber identity number of the terminal device; the network device sends a second message to a blockchain handling function network element, where the second message includes the first subscriber identity number of the terminal device and is used to query routing information of subscriber data associated with the first subscriber identity number; and the network device receives, from the blockchain handling function network element, the routing information of the subscriber data associated with the first subscriber identity number, where the routing information is used to address the subscriber data associated with the first subscriber identity number.