Abstract: The influences of annealing, amorphous ribbon length, AC frequency and magnetic field intensity on the giant magneto impedance effect of Fe78Si9B13 amorphous ribbons were studied by means of a 4248A impedance analyzer. The results show that the impedance rangeability of the amorphous ribbons could be enhanced after annealing. The impedance increased with the increase of the ribbon length and the AC frequency, and decreased with the increase of the magnetic field intensity. The impedance rangeability was enhanced with the increase of the ribbon length, AC frequency and magnetic field intensity.