The term translation is inevitably restricted by the arbitrariness and invariability of Saussure's linguistic signs because it is a thinking process of transforming linguistic signs of source language terms into those of target language terms.From the perspective of the arbitrariness and invariability of Saussure's linguistic signs,this paper discusses "current translation method" and "translation method of looking for equivalent" for terms,and draws the following conclusions:Saussure's arbitrariness inference of linguistic signs is a theoretical foundation of "current translation method";Saussure's invariability inference of linguistic signs is a theoretical foundation of "translation method of looking for equivalent";"current translation method" is suitable for translation of source language terms having no equivalents in the target language and "translation method of looking for equivalent" is suitable for translation of source language terms having equivalents.Misapplying "current translation method" to translation of source language term having equivalent in the target language is the major cause of the mistranslation of terms at present.