A device identifier (ID) obtaining method, a terminal, and a network device, where the method includes sending, by a terminal to a network device, a first message used to obtain a device ID, where the device ID is used to globally identify the terminal uniquely, receiving, by the terminal, an encrypted key pair sent by the network device, where the key pair includes a first public key and a first private key, receiving, by the terminal, information sent by the network device, where the information is used to identify that the first public key is the device ID of the terminal, and determining, by the terminal, that the first public key is the device ID.