A monitoring method and system based on a magnetic field of a loudspeaker are provided. This method includes: collecting a magnetic field signal near the loudspeaker, and converting the magnetic field signal into a magnetic field digital signal; converting the magnetic field digital signal into a speech signal and removing an interference from the speech signal to obtain a filtered speech signal; removing noise in the speech signal, and performing short-time inverse Fourier transform on a speech power spectrum to obtain a denoised speech signal; equalizing response of the denoised speech signal to each frequency to convert the speech signal into an intelligible speech audio signal; and recognizing the speech audio signal and converting the same into a text content.