The invention provides a data authentication system, which comprises a management server, at least one mirror image server and an authentication server, wherein the management server is used for receiving a first communication connection request, and transmitting a first digital certificate and a second digital certificate in the first communication connection request to the authentication server; the at least one mirror image server is used for receiving a second communication connection request, and transmitting the second digital certificate and the first digital certificate in the second communication connection request to the authentication server; the authentication server is used for judging whether the management server and the at least one mirror image server pass authentication or not, and if the management server and the at least one mirror image server pass the authentication, a communication connection is allowed to be established between the management server and the at least one mirror image server. The invention also provides a data authentication method. According to the technical scheme provided by the invention, the safety of patient information in the management server and the at least one mirror image server can be ensured, and therefore, the patient information in the management server and the at least one mirror image server is prevented from being illegally read, and illegal information is prevented from being written in the management server or the at least one mirror image server.