Bank card transaction method and system for performing password authentication through mobile phone

The invention relates to a bank card transaction method and a bank card transaction system for performing password authentication through a mobile phone. The method and the device support safe consumer transaction performed in a point-of-sale (POS) terminal bank card payment system without password input equipment, wherein the bank card payment system comprises the POS terminal, an acquirer, a background system, an issuing bank, a cardholder registration system and a registered cardholder database; the background system is connected with the registered cardholder database and a short message gateway of a mobile operator network; a cardholder registers through the cardholder registration system to open a function of performing password authentication through the mobile phone; when transaction is performed at the POS terminal without the password input equipment, password information is transmitted to the background system through the mobile phone; and the background system matches the cardholder transaction information with the password information and submits the authentication of the issuing bank to finish the transaction, so that the safety of performing swiped transaction by using the POS terminal without the password input equipment can be improved.