High performance polymer composites with superior properties may be obtained by reinforcement of nanostructures such as graphene (Gr), hexagonal boron nitride nanosheetHexagonal boron nitride nanosheet (h-BNNS) (h-BNNS), andCarbon nanotube (CNT) carbon nanotube (CNT). The properties of the resultant composites are majorly influenced by the reinforcement mechanism and dispersion of the reinforcement into polymer matrix. The current research aims to use molecular dynamicsMolecular dynamics (MD) simulations to study the reinforcement mechanism and dispersion of theHexagonal boron nitride nanosheet (h-BNNS) h-BNNS into polyurethane (PU) matrix. Firstly, atomistic models have been prepared in Material Studio environment. h-BNNSHexagonal boron nitride nanosheet (h-BNNS) is reinforced into the PU matrix and a representative composite has been created using the amorphous cell module. The prepared representative composite is further simulated using the forcite module to obtain the properties of h-BNNSHexagonal boron nitride nanosheet (h-BNNS) reinforced PU nanocompositeNanocomposite. Furthermore, a model was created by random reinforcement of h-BNNS in the 0.3 weight percentage (wt.%) of h-BNNS. In the developed model, dispersion was ensured using the various types of energies generated in the developed model. Finally, the developed model was simulated for various mechanical propertiesMechanical properties. Results revealed that elastic modulus, bulk modulus, and shear modulus of 0.3% h-BNNSHexagonal boron nitride nanosheet (h-BNNS) reinforced PU nanocompositeNanocomposite were increased by 50.54%, 76.17%, and 170.9% respectively.