The invention discloses a master/slave mode-based one-plant and more-station ordered power utilization control system and method. The system comprises a master station, a master terminal and slave terminals, wherein the master station issues a master terminal control model to the master terminal; the master terminal takes charge of receiving a master terminal control model issued by the master station and transferring the master terminal control model to the slave terminals as a master control node, and simultaneously receives collected data uploaded from the slave terminals; the slave terminals are miniature load control terminals; the master station does not need to manage the slave terminals; the slave terminals are connected with controlled equipment through corresponding control modules; the slave terminals are connected to collection modules, achieve dispersed collection of plant loads and upload load data to the master terminal; the slave terminals have a relay control function, achieves multi-path relay control at a medium or short distance; and in actual control, the controlled equipment of the slave terminal achieves tripping operation according to a control round sequence. Unified power brownout index-oriented substation control in one plant is achieved; and fine control requirements on loads in a large-range plant are met.