Directing against the problems existing in control system of 2×350 MW units in the first-phase project of Huaneng Rizhao Power Plant,such as the slow response speed to load,and unable to satisfy the requirements of AGC function of power grid,etc.,the control logics related to the coordinated control of units,the superheated steam temperature,the primary air pressure,the primary air flow rate of coal pulverizer etc.have been optimized,and the parameters of regulator in related control systems being set,adopting widely the variable structure and variable parameter controls,enhancing control quality of control system for units.After putting the coordinated control mode into operation for units no.1 and no.2,test of variating load range,and load-increasing rate,as well as assessment test of AGC have been carried out respectively.Results show that the control indices of coordinated control system after optimization all can satisfy the AGC functions required by the power grid,the load variation range is 175~350 MW,the load variating rate reaches 4~5 MW/min,the main parameters of units can satisfy the requirements of operation.