The invention discloses a reactive voltage control method of a power network. The power network comprises a station near a voltage sending end and extra-high voltage stations, wherein the extra-high voltage stations are connected with the station near the voltage sending end via a circuit; the control method comprises the steps of setting a full-connection mode reactive voltage control method; controlling reactive power output of a unit according to transmission power of the station near the voltage sending end; setting a reactive switching control method; adjusting the reactive power absorbed by the extra-high voltage stations from a power network system according to medium-voltage side voltage of the single extra-high voltage station or all extra-high voltage stations; and setting an extra-high voltage bus voltage control method and setting a lower limit of the voltage in a peak mode and an upper limit of the voltage in a valley mode. The stability of extra-high voltage power network equipment is improved through setting the full-connection mode reactive voltage control method, the reactive switching control method and the extra-high voltage bus voltage control method; and the service life of the power network equipment is prolonged.