Terrestrial digital television global broadcast roaming method and system

The invention provides a terrestrial digital television global broadcast roaming method, comprising the steps that: an operator configures an identification code (ID) capable of being uniquely identified by a digital television operator within a global range to a digital television mobile terminal, and storage, management and update function modules of user accounts and position information capable of mutually cooperating are established by operator networks to enable a mobile terminal to use a digital television broadcast service function within a non-registration place operator network range; and each user terminal and each operator have public keys and private keys, so that the communication security and reliability are improved on the premise of achieving roaming service.