The invention discloses an adjusting mechanism for the gap between two cutting edges of a pair of flying shears. In the structure that two pairs of shears are arranged up and down, one pair of shears is fixedly arranged while the other pair of shears is jointed on a guide pole of a gap adjustment mechanism in the gap adjustment direction; the gap adjustment mechanism further comprises a machine frame for guiding the guide poles, eccentric shafts equipped on the machine frame part at the driving ends of the guide poles, and a connecting piece connected between the eccentric shafts and the driving ends of the guide poles; the descending degree of freedom of the guide pole is restrained; and the axial lines of the eccentric shafts are orthogonal to those of the guide poles. The adjusting mechanism has compact structure and high adjusting precision.