The invention provides an anti-harmonic frequency measuring method and device based on sinusoidal filtering. The method comprises the following steps of: performing low-pass filtering on frequency signals of a power system to obtain low frequency signals of the power system; performing sinusoidal filtering on the low frequency signals of the power system to obtain frequency measuring signals of the power system; and performing frequency measurement processing on the frequency measuring signals of the power system to obtain real-time frequencies of the power system. According to the anti-harmonic frequency measuring method and device based on sinusoidal filtering, when the frequency measurement processing for the power system is performed, the high frequency signals therein are first eliminated, and then the interference of the low frequency harmonics therein is eliminated, so that the frequency measuring result is more accurate.