The invention discloses a two-factor authentication mobile payment method in an offline card mode and a system thereof. The method comprises steps: offline card password-free payment is selected through an application program on a mobile terminal provided with a mobile operator SIM card, the mobile terminal sends a payment request to the traditional payment platform via the SIM card, and the traditional payment platform recognizes and stores the identification code of the SIM card; a financial card payment device receives the payment request sent by the mobile terminal, and a payment message for payment is generated; the payment message is sent to a POS terminal, the payment message is sent to the traditional payment platform via a POS operator, the traditional payment platform compares the payment message with the stored identification code of the SIM card, if matching, the transaction is completed, and if not, the transaction is denied. The payment is authenticated and validated through the identification code of the mobile operator SIM card and the payment message via two independent telecommunication channels, and the safety grade can be ensured to be no lower than that when payment authentication is carried out through inputting a password.