A method for security authentication of a power system includes transmitting, by at least one power system, a signal for requesting performing authentication on at least one remote control server or an external terminal with which the power system is to perform communication, to an authentication server, receiving, by the power system, an authentication certificate generated by the authentication server, and perform authentication on the remote control server or the external terminal by using the authentication certificate, and when authentication is completed by the authentication server, performing communication, by the power system, with the authentication-completed remote control server or the external terminal through an open-type communication network.