Abstract: For studying the impact of source-load power extreme disturbance on microgrid power flow and frequency, this paper proposes a three-phase power flow optimization control model for islanded microgrid by considering both current-controlled mode and voltage-controlled mode of micro power source as well as the static frequency-voltage characteristic of the source and load. This model uses the active power loss minimization in normal state as objective function and takes the power flow and frequency of the normal state and extreme disturbance state of the source and power under the next time as safety constraints. The power regulation of the optimization model includes the primary regulation ability of the source and load frequency-voltage characteristic, the secondary regulation ability of the controlled power source under normal conditions, and the primary regulation ability of the source and load during the extreme disturbance. The predictor corrector primal dual interior point method is used to solve the model. The simulation results of the IEEE 33 node modified system were used to demonstrate the effectiveness of the proposed model.