The coupled structure of metal nanoparticles and metal film has more superior physical properties than unit structure. In order to provide theoretical basis for experimental study on the application of silver nanocube coupled with silver film in sensing, the electric properties of the coupled system were analyzed using FDTD excited at the wavelength of 514.5 nm. The results show that the electric field distribution of the coupled structure of silver nanocube and silver film was affected by the size of silver nanocube and the thickness of the dielectric spacer between silver nanocube and silver film. The local electric field of the coupled structure was stronger than that of unit of silver nanocube. When there was no dielectric spacer, the local electric field was mainly localized on the upper surface of the silver nanocube for the coupled structure. When there was dielectric spacer, the local electric field would be partially localized in the dielectric spacer. Therefore, the ideal local electric field can be obtained by adjusting the size of silver nanocube or the thickness of spacer between silver nanocube and silver film for requirement.