The transmission of light through a single nanoslit milled in the metallic film is enhanced by using an array of nanocavity antennas. It is shown that transmission efficiency through a $25\text{-}\mathrm{nm}$ -wide silver nanoslit can be enhanced to $\eta =151$ when six pairs of nanostrips are placed $50\mathrm{nm}$ away from the input surface of the silver film at wavelength ${\lambda }_0=1\mu \mathrm{m}$ . The influences of both the nanoslit position and the slit-to-strip distance on the extraordinary transmission are investigated, and the physical mechanism is explained.