Abstract: Total spectra and subsection scanning for component analysis in the metal plates and phosphide tunica using X-ray diffractometer were carried out. Based on the existence of the chemical phases of Zn3(PO4)2·4H2O, area integrals or intensities of the Zn3(PO4)2·4H2O phase from the faces of (020) and (241) are obtained and face ratio of phosphide tunica of the samples can be calculated.