The embodiment of the invention discloses a unit integrated control method and system based on the area control error of a power grid. The unit integrated control method based on the area control error of the power grid comprises the following steps: calculating the area control error ACE according to the power changes between interconnected power grids and the frequency changes of the power grids; obtaining the adjusting times of the unit according to the area control error ACE combined with a dead-time non-linear function of historical data of the power grid operation; obtaining the load adjustment range according to the adjusting times, and predicting the pressure variation of the main steam pressure of the unit caused by AGC adjusting; calculating the deviation value between the set value of the main steam pressure and the measured value of the main steam pressure of the unit, and performing summation operation on the deviation value and the predicted pressure variation to obtain the predicted fluctuation value of the main steam pressure; and controlling the unit adjustment speed according to the predicted fluctuation value of the main steam pressure. The invention judges the range of the action required by the unit and whether the energy of the unit is enough to ensure the performance of the adjustment or not in advance, and filters out unnecessary combustion adjustment atthe boiler side of the unit such as air, coal and water, so as to achieve the purpose of energy saving and consumption reduction.