With the coupling relationship between active power and reactive power in power system becoming stronger, the control mode that automatic generation control (AGC) and automatic voltage control (AVC) operate separately may influence the control effect. Considering of the different control periods of AGC and AVC, this paper proposes a coordinated control method of AGC and AVC with a connection on the time scale of minute level and second level. On the minute level, an optimal power flow model of active power and reactive power associated together is established, a AGC and AVC associated optimization control method is proposed. On the second level, the respective control strategy of AGC and AVC is improved and a coordinated correction control method of AGC and AVC is proposed. Simulation is made to verify that the method proposed meets the respective control objective of AGC and AVC. At the same time, it can realize the economic operation of power system, restrain the mutual influence of AGC and AVC, and promote the mutual support between AGC and AVC.