The seismic vertical resolution of sand shale interbed is very important to the exploration of lithologic reservoirs. Band limited seismic wavelet and its resolution are discussed. The theoretical model of sand shale interbed shows that the definition of !/4 vertical resolution is not reasonable while!!/8 vertical resolution is much more
reasonable. The exploration practices of lithologic reservoirs showthat the vertical resolution may be !/16 when there is a big set of shale which includes thin sandstone. The research result provides theory foundation for the lithologic reservoir exploration of sand shale interbed.