Abstract: The contact angles of molten Al and saveral Al alloys on polycrystal-line-Alumina were measured by sessile drop method in vacuum.The effects of temperature and currently used alloying elements such as Mg,Cu,Si and Fe on the wettability of Alumina/Al system wars investigated.The wetting phenomena and interfacial reactions were observed and analyzed with metallographic microscope,microprobe x-ray diffraction,atom absorption spectroscop9 qualitative analysis,etc.