The invention provides an ultrahigh voltage substation simulated operation verifying system, comprising a voltage regulator, an intermediate transformer, a compensating capacitor unit and a control unit; the voltage regulator regulates power voltage and transmits to the intermediate transformer; the intermediate transformer transforms the voltage and supplies it to a transformer under test; the intermediate transformer a single multi-position output transformer; the compensating capacitor unit is hung to a bus between the intermediate transformer and the transformer under test through a reactive compensation contactor unit for reactively compensating the system; the control unit acquires compensation capacitance to be input according to parameters of the intermediate transformer and parameters of the transformer under test and controls the reactive compensation contactor unit to act so that the compensating capacitor unit is put in corresponding compensating capacitance; an output position of the intermediate transformer is adjusted according to required input voltage of the transformer under test.The primary side power supply requirement of an ultrahigh voltage substation can be met, and high voltage is simulated with low voltage and low current so that secondary side undergoes various index tests at ultrahigh voltage.