The growth of perylene and tetracene on Ag (110) has been studied by the ultraviolet photoemission spectroscopy (UPS) and low-energy electron diffraction (LEED). The LEED results illustrate that an ordered C(6×2) structure can be observed when the thickness of perylene is about one monolayer (thickness of 03n m), and an ordered C (4×2) structure for tetracene with a thickness of one monolayer. From the measurements of UPS, four emission features of perylene are located at 35, 48, 64 and 85eV below the Fermi level respectively, and f our characteristic peaks, for tetracene, are located at 34, 49, 59 and 9 4 eV below the Fermi level. The angle_resolved ultraviolet photoemission spectro scopy measurements show that both perylene and tetracene near the interface are parallel to the substrate, the tetracene molecule is along ［110］ direction.