Abstract: The present disclosure discloses a method and system for measuring a frequency characteristic of a capacitor voltage transformer, and a terminal. The technical solutions are: collecting, with a transient voltage of a power system as an excitation voltage on a primary side of the CVT, a response of a secondary side of the CVT to the transient voltage, to obtain a transient voltage response; performing spectrum analysis on the transient voltage response, identifying a valley point and a peak point, and extracting a valley frequency corresponding to the valley point and a peak frequency corresponding to the peak point; and calculating a stray parameter of the CVT according to the valley frequency and/or the peak frequency, to obtain a frequency characteristic measurement result. According to the present disclosure, online measurement of the frequency response characteristic of the CVT can be implemented.