A GMI bio-magnetic measuring device based on a magnetic-bead concentration and a simulated lesion shape, includes an impedance analyzer, a Helmholtz coil, a metallic fiber, a fluxgate uniaxial magnetometer, a data acquisition card, a computer, a magnetic-bead-concentration adjustable platform and a lesion shape simulation platform. The metallic fiber is fixedly disposed on the magnetic-bead-concentration adjustable platform or the lesion shape simulation platform. Two terminals of the metallic fiber are electrically connected with a connection terminal of the magnetic-bead-concentration adjustable platform or the lesion shape simulation platform, and then are electrically connected with an input end of the impedance analyzer. An output end of the impedance analyzer is electrically connected with the computer. The magnetic-bead-concentration adjustable platform or the lesion shape simulation platform is placed at the interior of the Helmholtz coil. A probe of the fluxgate uniaxial magnetometer is disposed at the interior of the Helmholtz coil.