The motion of a semi-infinite incompressible fluid caused by the sinusoidal oscillation of a plane flat plate is termed Stokes' second problem. With the assumption of zero velocity normal to the plate and thus simplified Navier-Stokes equations, Stokes' well-known result can be obtained by analytical approach. In this paper, behaviors of the fluid are to be studied by solving the full Navier-Stokes equations through numerical simulations.