An electric power plant general control system for controlling power generating units. A generating unit (GU.sub.2) can operate part of the auxiliaries based on an automation command outputted from a unit computer (UC.sub.2) having a sequence function portion. The generating unit operates the remaining part of the auxiliaries based on an operation command outputted from an operation board (OB.sub.2) without a sequence function portion, the operation board disposed separately from the unit computer. A general automation computer (GAC) is connected with an upper system of the unit computer, and an operator command is inputted from an interactive apparatus (I/F.sub.4). The general control system is provided with a mock-up portion (Moc) equivalent to the sequence function portion disposed on the side of the auxiliaries controlled by the automation command outputted from the unit computer. The operation signal from the general automation computer is outputted to the unit computer and the operation board.