The invention relates to the technical field of electrical equipment insulation state monitoring, in particular to a novel ultrahigh frequency partial discharge sensor performance detection method andsystem. The method comprises the steps: a transfer function of a GHz transverse electromagnetic wave transmission chamber is acquired; after a tested sensor is placed in the GHz transverse electromagnetic wave transmission chamber, an ultrahigh frequency pulse generator sends out a predetermined pulse signal with a predetermined amplitude and a predetermined waveform; a radio frequency coupler proportionally divides the predetermined pulse signal into an output pulse signal and a coupling pulse signal; the GHz transverse electromagnetic wave transmission chamber generates an excitation electric field according to the output pulse signal; an ultrahigh-speed signal acquisition device simultaneously acquires a response signal generated by the tested sensor according to the excitation electric field and the coupling pulse signal output by the coupling end of the radio frequency coupler; and the equivalent response height of the tested sensor is obtained according to the transfer functionof the GHz transverse electromagnetic wave transmission chamber, the response signal of the tested sensor and the coupling pulse signal. The method can reduce the deviation of the final measurement result.