NFC-based intelligent lock offline password changing control method

The invention relates to an NFC-based intelligent lock offline password changing control method. A mobile phone and an intelligent vehicle lock adopting the method each have the NFC communication function. The intelligent vehicle lock comprises a password generator and a code generator. The method comprises the steps that when the lock is prepared to be closed, the mobile phone gets close to the intelligent vehicle lock, and a changing directive is sent to the intelligent vehicle lock; after the intelligent vehicle lock receives the directive, the password generator inside the vehicle lock is started, the code generator takes effect, passwords and serial numbers of the vehicle lock are changed with new ones at the same time, and the intelligent vehicle lock is sent to a background management system through the mobile phone; the background system performs querying, if the new serial numbers are available, the new serial number and passwords are used for updating original database information, meanwhile, a lock