The magnetic dynamic interaction in ferromagnetic microwire arrays has been studied based on thin Co-based glass-coated amorphous microwires. The longitudinal hysteresis loops of the microwire arrays consisting of different number of wires have been measured statically with no current flowing through the arrays and dynamically with ac current flowing through the arrays. The results show that with the number of wires increases the transverse anisotropy of the arrays has been enhanced, especially when an ac current was applied to the arrays, an additional circumferential anisotropy was induced. The results are explained by a domain unification effect in the form of domain wall displacement. Moreover, the changes in the magneto-impedance effect with the number of wires in the arrays indicate that the domain unification effect is frequency dependant and related to the dimension of the arrays. The domain wall motion contributes to the magneto-impedance up to a critical frequency beyond which only domain rotation occurs. Below the critical frequency, the initial permeability of the arrays increases with the increase of the number of wires while above the critical frequency, the trend inverses. The magneto-impedance response of the microwire arrays is a consequence of the dynamic interaction of domain unification and eddy current.