This study comprehensively investigates tensile-compressive and shear effects of van der Waals (vdWs) interactions on free vibration of cantilever bilayer graphene nanoribbons (CBGNRs) to be answered to this question that how and how much the effects of each of these factors are in comparison with the other one when they are considered simultaneously. To this end, the CBGNRs are modeled based on sandwich beam theory in which each nanoribbon plays role of sandwich layer and vdWs interactions are equivalent to the sandwich core. At the first step a geometrical–analytical method is presented to calculate the equivalent tensile-compressive and shear moduli of vdWs interactions. After that, a set of coupled governing equations of motion and boundary conditions are derived and solved numerically by the harmonic differential quadrature method. This study shows that for designing multi-layer GNR based applications, such as resonators, the shear effect of vdWs interactions must be considered.