The invention provides a method and a device for electronic authentication based on a mobile terminal. The method comprises the following steps of receiving a certificate application request which is initiated on the mobile terminal by a user; judging whether a hard medium certificate of the mobile terminal is stored locally according to user side information in the certificate application request; if the hard medium certificate of the mobile terminal is stored locally, obtaining a soft medium certificate according to the hard medium certificate and the certificate application request and sending the soft medium certificate to the mobile terminal; utilizing the soft medium certificate to carry out signature verification on a signed file and authenticating the mobile terminal according to the user side information; when the signature verification of the file and the authentication of the mobile terminal are passed, utilizing the hard medium certificate to re-sign the signed file; and verifying the file resigned by the hard medium certificate and feeding a verification result back to the mobile terminal. According to the method and the device, a problem of low security of the soft medium certificate is solved and the requirements of the user for the signature of the hard medium certificate are also met.