Abstract: The strict size of polycrystalline translucent alumina ceramic are tube is paramount importance for the production of long life high, pressure sodium lamp, while lamp efficacy is affected by transmittanoe of light in the ceramic are tube. The present paper studied the processing of alumina tube formed by isostatio pressing. The effect of the characteristics of starting materials, additives and heating condition on the miorostruoture and light transmittance of the alumina arc tube obtained were investigated. Arc tubes with strict size, uniformly sized grains and a total light transmittance of 94~95% are now fabricated in mass production.