In this study, nanosilica/crosslinked Polyacrylamide (PAM) microsphere with a core-shell structure is designed to make a functional material, where nanosilica provides the rigidity, stiffness and strength, the crosslinked PAM provides the flexibility and elasticity. The structure mentioned above make the resulting microspheres to be able to enter, expand, shut off and be removed from deep layers of oilfields. A methodology to create the nanosilica/crosslinked PAM microsphere with a core-shell structure has been developed, and molecular dynamic (MD) simulations are applied to successfully study the interaction between the microsphere and water in aqueous solution of nanosilica/crosslinked PAM microsphere and its swelling behavior. Results including the interaction energies (E-inter) between nanosilica and crosslinked PAM, E-inter between the microsphere and water molecules, radius of gyrations (R-g) of the microsphere, the radial distribution functions of microsphere-water pairs, the mean square displacements and the diffusion coefficients (D) of water are calculated and analyzed in detail. The experimental results of particle diameter tested from dynamic light scattering have been used to verify the simulation results of swelling behavior. [GRAPHICS] .