The invention relates to a method and system for measuring the frequency of a single coil vibrating instrument, wherein the method comprises the following steps: firstly, exerting alternating swept-frequency exciting signals on the two ends of a frequency measurement coil in the single coil vibrating instrument so as to drive a steel string to perform mechanical vibration; then, canceling the swept-frequency exciting signals, and forming induced voltage signals at the two ends of the frequency measurement coil, wherein the frequency of each induced voltage signal is consistent with that of the mechanical vibration of the steel ring; carrying out data acquisition on the induced voltage signals by virtue of an AD (analog-digital) converter, and carrying out FFT (fast fourier transform algorithm) spectrum analysis on the signals (acquired by the AD converter) by virtue of a digital signal processor; and finally, extracting the basic frequency signals in the spectrum according to a maximum value method, and then obtaining the frequency measurement value. The method provided by the invention has the advantages of increasing the anti-interference capacity, and improving the accuracy and reliability of frequency measurement of the single coil vibrating instrument.