The invention discloses an apparatus for calculating a capacitor voltage transformer ferromagnetic resonance frequency. The apparatus comprises a power supply circuit, a damping circuit, a secondary winding short circuit operation circuit, a secondary winding short circuit control circuit and a ferromagnetic resonance frequency calculation circuit, wherein the power supply circuit is used for providing a test voltage and providing a primary voltage for the ferromagnetic resonance frequency calculation circuit; the damping circuit is input into a capacitor voltage transformer which does not include a damper according to a second control signal of the secondary winding short circuit control circuit; the secondary winding short circuit operation circuit is used for receiving a first control signal, controlling generation and elimination of a secondary winding short circuit of the capacitor voltage transformer which does not include the damper and outputting a secondary current to the ferromagnetic resonance frequency calculation circuit; the secondary winding short circuit control circuit is used for controlling short circuit and elimination time of a secondary winding of the capacitor voltage transformer which does not include the damper and a preset time-delay threshold of damping circuit access; and the ferromagnetic resonance frequency calculation circuit is used for calculating a ferromagnetic resonance frequency according to the primary voltage, the secondary current and a secondary voltage signal.