The bilayer structures of graphenes and boron nitride nanosheets (BNNSs) with different interlayer spacings are optimized, and their Young's moduli are calculated using the molecular dynamics method. The optimized results indicate that the optimal interlayer distances are about 0.343 nm for bilayer graphenes and 0.354 nm for bilayer BNNSs. A comparison of the binding energy, van der Waals interactions between layers, and radial distribution function (RDF) revealed that bilayer BNNSs can achieve a more stable combined structure than bilayer grap...