Abstract: A calculation formular of the polarization alignment angle ofearth station antenna,receiving liner polarized radiation signal from thecommunications satellites,has been given in this paper.The polarizationalignment angle of the antenna of an earth station,which operates in theliner polarized communications system,is variable upon its location.By useof coordinate transform,a pragmatical formular is produced.In the installationand adjustment of an earth station,the polarization alignment angle can beeasily calculated as far as finding out the announced longetude of the satellitelocation and bore-sight of its antenna,and the longetude and lagitude of thebeing installed station.The formular given in this paper is not only correctefor the TV receiving stations,but suitable for the communications earthstations as well.