The invention discloses a pilot frequency generation circuit for testing the secondary circuit impedance with the pilot frequency admittance method. The pilot frequency generation circuit comprises a driving amplification phase-inverter circuit, a VR reference point circuit and a push-pull output waveform generation circuit; the driving amplification phase-inverter circuit comprises a driving amplification circuit and an inversed voltage follower circuit, wherein the driving amplification circuit is connected with the inversed voltage follower circuit, the inversed voltage follower circuit is connected with the VR reference point circuit, and the VR reference point circuit is connected with the push-pull output waveform generation circuit. By means of the pilot frequency generation circuit, functions of the circuits are explicit and easy to achieve, DSP one-pin control is achieved through simple circuits for driving amplification, inversed following, to-ground reference point heightening, push-pull output, filter shaping and the like; in other words, the needed 1.6 KHz standard sine can be generated; the pilot frequency generation circuit has the advantages of being fewer in element, simple in circuit, good in stability, high in safety and the like.