The invention discloses a magnetic sensor based on an amorphous
magnetic core coil and a working method thereof. The sensor consists of an amorphous
magnetic core magnetic sensitive element and a working circuit, wherein the amorphous
magnetic core magnetic sensitive element is a block magnetic core (1) formed by laminating a sheeting amorphous material; an
induction coil (2), an insulating layer (3) and a biased coil (4) are sequentially arranged outside the block magnetic core (1); the working circuit consists of a biased circuit (5), an oscillating circuit (6) and a frequency-measuring circuit (7); and the
induction coil (2) is the
induction coil in the oscillating circuit (6). The working method comprises the following steps of: adjusting the working current of the biased coil to obtain the
magnetic field strength H0 when the amorphous magnetic core magnetic sensitive element is under the
magnetic field strength of 1 to 200e; placing the amorphous magnetic core magnetic sensitive element in a
magnetic field to be measured, and measuring the
resonance frequency fx output by the oscillating circuit; and obtaining the magnetic
field strength Hx when the
resonance frequency is fx according to the formula that fx is equal to 5.94Hx+36.51, and obtaining the strength
delta Hx of the magnetic field to be measured according to the formula that
delta Hx is equal to Hx-H0. The magnetic sensor and the method can be widely used for high-precision measurement on a weak magnetic field.