Abstract: Based on the introduction to the characteristics of the control over 1 000-MW ultra-supercritical once-through boilers, the problems of the coordinated control system existing in the 1 000-MW unit in on power plant are analyzed. The control system optimization strategies on main steam over/under pressure and tube wall overheating in load variation are put forward. In addition, the optimized control strategies and parameters for main control circuit, feedwater loop and fuel loop are proposed. Meanwhile, the boiler sliding pressure curve is optimized to minimize the throttling losses of the main steam valve and improve the economic performance of the unit. Finally, the effects of the implementation of these strategies are analyzed and summarized.