The present disclosure provides a method and a system for offline verification code generation based on a smart door lock system. The method may include in response to an unlocking event, recording, by a mobile terminal, a trigger time of the unlocking event; in response to the unlocking event, sending, by the mobile terminal, a request for unlocking verification information to a cloud server, wherein the request for the unlocking verification information is used to request the cloud server to return a verification code of a smart door lock, and the unlocking verification information includes a private key seed of the smart door lock and the trigger time; and receiving, by the mobile terminal, the verification code of the smart door lock for opening the smart door lock generated by the cloud server based on the private key seed and the trigger time.