The invention discloses a mixed power quality treatment method. In an active part, at least two groups of SVG and at least two groups of APF are connected to a three-phase power network in a transformer isolation mode, wherein the SVG mainly compensates reactive current, the APF compensates harmonic current, and when the voltage dips seriously, the APF can also serve as a reactive generator to make up for the deficiency of the SVG capacity to support the voltage; and in a reactive part, a large-capacity directly hung SVC combined by TCR, TSC and FC is directly connected to the three-phase power network for reactive compensation, the TCR is subjected to three-phase unbalance control so as to compensate three-phase unbalance, a thyristor-switched capacitor TSC provides large-capacity capacitive reactive power, a fixed capacitor-compensated FC provides small-capacity reactive power, and the fixed capacitor-compensated FC also serves as a main subharmonic filtering subcircuit of a thyristor-controlled reactor TCR for coordinative comprehensive compensation and harmonic treatment of a power system.