Amino-silane coupling agents are used to improve adhesion to polyamide-based composites. This paper aims to study the influence of polyamide 6 moisture content on the interfacial strength between the polyamide and amino-silane-coated aluminum. A coupled experimental and simulative approach is applied that enables the interfacial strength to be taken separately from the moisture-dependent mechanical behavior of polyamide 6. Lap joints of polyamide 6 and aluminum, functionalized by 3-(2-aminoethylamino)propyl trimethoxy silane, are tested at three different polyamide moisture conditions. Afterwards, numerical simulations of the lap shear experiments are carried out to identify the parameters for a mechanical model of the interface. Subsequently, the dependence of polymer's properties on the moisture content is investigated by different sets of parameters of an applied inelastic material model. Finally, an analysis of the interfacial parameters proves and characterizes the dependence of the joint strength on polyamide moisture content. It is found that the lower the moisture content of the polyamide, the higher the interfacial strength.