Yunnan power grid is with balanced hydropower and thermal power sources， which has brought a favorable opportunity for online hydro-thermal coordinated control. According to characteristics of the load of Yunnan power grid， the hydro-thermal AGC units are divided into different groups by the regulation characteristics， and each group adopts different control mode at different time zone， which optimizes hydro-thermal coordination scheduling of AGC units effectively. Test run result shows that the strategy can adapt the characteristics of Yunnan power grid to improve the control performance of AGC.