The invention discloses a giant magneto-impedance effect sensing probe based on a flexible circuit board. The sensing probe belongs to the technical field of magnetic field detection and is characterized in that the probe uses a double-layer flexible circuit board comprising two coincident straight wires with a longer length than an end effect critical length of a magnetic alloy wire or belt. Thetwo wires are in short connection through vias at one end, and the other end of each wire leads out a twin conductor by means of a bonding pad to provide a sensing signal. One wire is disconnected for a certain gap in the middle, and the middle section of a magnetic alloy wire or a magnetic alloy belt is accessed on two bonding pads at the two sides of the gap by constant temperature welding spots. The magnetic alloy wire or belt is straightened along the wire direction and attached on the surface of the flexible circuit board by virtue of an inviscid insulating film, and is fixed by a viscous insulating film to constitute the integral sensing probe. The sensing probe has a sensitive giant magneto-impedance effect within 10MHz to 30MHz, and the machined probe has consistent measuring properties and is strong in anti-interference performance when in application.