Abstract: Energy-saving generation dispatching（ESGD） is the trend of dispatching mechanism in China.The optimization of ESGD should take both the coal consumption and network loss into consideration.However,with the expansion of the modern power system,the optimization problem becomes more and more complicated.Considering the effect of coal consumption and network loss synthetically to the system energy consumption,the paper developed a comprehensive coal consumption incremental principle,and the ESGD optimality conditions for thermal power units based on that principle were given out.By using the optimality conditions the optimization of ESGD was assessed simply.Then the paper proposed an ESGD algorithm that combined the equal coal consumption incremental principle and OPF（optimal power flow）.It solved the constraint conditions efficiently and reduced the energy consumption.The compute capacity to solve the problem became controllable at the same time.The paper proved the principle and algorithm by 10 units of the IEEE 118 system.The results show that the optimality conditions and algorithm can solve the constraint conditions and reduce the coal consumption and network loss.The method satisfies the optimization of ESGD.