Abstract: A method for measuring weak magnetic fields using the Lissajous figure technique was proposed，and
a relationship between magnetic field intensity and frequency was derived．A homemade weak magnetic field
measurement device was designed and fabricated，comprising a TGG magnetic field sensing system，a
transimpedance amplification and acquisition system，a signal " voltage-frequency" conversion system，and a
frequency measurement system．The transimpedance amplification and acquisition system amplified the signal
by a factor of 10 11 ．The experimental instrument achieved a measurement resolution of 10 Hz，with a minimum
measurable magnetic field strength of 11 μT and a measurement error of less than 3 μT，which decreases as the
measured magnetic field intensity increases．The instrument can accurately measure the Earth＇s magnetic field
and eliminate its influence in other magnetic field measurements．Finally，the error conditions of the homemade
instrument system were analyzed．
