Corrugated cardboard is very sensitive to atmospheric conditions. The aim of this work is to study the effects of these parameters, in fact the relative humidity (RH), on the mechanical behaviour of a sandwich structure of the corrugated cardboard type. For that, tensile tests were used under various rates of relative humidity. In high rates of moisture, the instrumentation must be adapted. A preliminary comparison of several measurement methods of the mechanical properties was carried out. It made it possible to validate the method of strain measurement using the measurement of the displacement which requires a minimal handling of the specimen. During this study, the effect of the water content on the mechanical properties is presented. Moreover, the viscoelastic character coupled with the damage of this material is high lighted.