First order reversal curves (FORC) and intrinsic high frequency permeability spectra have been simulated and analyzed for '1 × 3' iron nanowire (NW) arrays with different interwire distances (D). Discrete interaction constants are found and gradually disappeared with increasing D value. The number of weak resonance peaks decreases with increasing D value. Two strong resonance peaks are found for each array with different D values: the lower one is ascribed to the 'edge mode'. The higher one is ascribed to the 'bulk mode'. The magnetic loss due to the edge mode cannot be neglected. The difference in bulk mode resonance in the simulated and the calculated are believed to arise from the interaction between NWs. It is believed that the local effective magnetic fields determine the orientation of magnetic moments in the equilibrium states, and consequently determine the high frequency intrinsic permeability spectra. FORC diagrams are helpful to reveal the distribution of local coercive fields.