In-situ growth of copper azide has endowed this highly sensitive primary explosive new life, but its mechanism study is not enough to support its in-depth study. Hence, azidation reaction was conducted on highly ordered copper nanowires array, which could provide effective channels for gas phase reactant (hydrazoic acid, HN3) to penetrate the solid, further study the mechanism of azidation reaction on copper azide nanowires array, and clarify the relationship between the microstructure and its azidation degree. Gas–solid in-situ azidation technique was used for this in-depth study. The effects of reaction temperature on formation of gaseous HN3 were studied by isothermal thermogravimetry. The azidation results were analyzed by SEM and XRD, the effects of the reaction time, diameter of copper nanowires array precursor and oxidation degree on the azidation degree were studied in detail. This work not only provided deep investigation on the azidation process, but also offered effective guidance for the synthesis of copper azide nanowires array.