The VOF(Volume of Fluid) method associated with Navier-Stokes equations and continuity equations of incompressible fluid was used to simulate the oscillation flow field of liquid in a rectangular tank. Conjugate residual(CR) algorithm and finite difference method were employed to solve NavierStokes equations and continuity equations, and donor-acceptor scheme was used to discretize the governing equation of fluid volume function. The wave position and velocity vectors during one period obtained by the computations were compared with theoretical results. Moreover, distribution curves of the wave position and velocity vectors for the first six oscillation periods of the liquid oscillation field were compared. The comparisons showed that the simulated evolutionary process of water wave oscillation field is consistent with theoretical results. Therefore, VOF method can be applied to simulate the oscillation flow field accurately .