The invention provides a torsion-type micro mechanical magnetic field sensor and a preparation method thereof. The torsion-type micro mechanical magnetic field sensor comprises a resonant structure component which comprises a resonance structure, a first insulating layer, an induction coil and a driving electrode, the first insulating layer is positioned on the surface of the resonant structure, the induction coil is positioned on the surface of the first insulating layer, and the driving electrode is suitable for driving the resonant structure by means of electrostatic driving to enable the resonant structure to be in a torsion resonant mode during working. The sensor works by means of electrostatic driving, and power consumption of devices is almost zero, so that the problem of temperature stability of the devices due to overhigh power consumption is avoided; according to electromagnetic induction laws, the sensor has excellent linearity in wide-range magnetic field measuring.