The effect on LPX radiation characteristics with a laser irradiating binary-layer (Au-Al) target is presented with or without a prepulse in this paper. It shows that abundant spectral lines of H-like aluminium ions and a varitey of impurity spectral linesemitting from the inner layer of Al are observed with a high spectral resolution due to the narrow linewidths. While without prepulse and the thickness of the outer layer of Au coated more than 200nm, only gold spectral lines emitted from the outer layer of Au coated more than 200 nm, only gold spectral lines emitted from the outer layer of Au are observed.