With large-scale energy storage stations constructed and being in operation, energy storage source effectively promotes power system dynamic regulating performance for its fast and high precision power control characteristics. Firstly, charging and discharging ability of energy storage stations aggregation is analyzed and the aggregation analysis algorithm of subarea division of power grid is proposed. The analysis results provide ancillary decision-marking proposals in fast power control, peak shifting in short time and load trend following. Secondly, it summarizes the control objectives of energy storage stations aggregation according to requirements of active power balance and power flow control for transmission and transformation in subarea division of power grid. It proposes dispatching strategy which includes charging and discharging state convert and power regulation on the basis of state of charge (SOC) for storage stations in equilibrium to calculate regulating volume in order to satisfy the control objectives in close loop. Finally, a case proves that it develops the aggregation and scale advantage of energy storage source, and thus solves problems in dispatching and control for subarea division of power grid.