By the wave superposition approach a method of enhancing the spatial resolution of the nearfield acoustic holography is proposed. According to wave superposition approach, the source strengths of fictitious sources placed on the fictitious surface which is near the hologram surface are obtained by measuring the hologram pressure signal, then these fictitious sources are used to realize the interpolation of acoustic pressure, finally, the reconstruction can be done by the interpolated hologram pressure. By this method the spatial resolution of the reconstructed image can be improved, the measurement workload is reduced, and the measurement process is simplified. The parameters affecting the interpolated result are reasonably chosen by numerical simulations and the availability of this method is proved by numerical simulations and experimental resuets.