Chinese classical poetry contains ＂untranslatability＂. The Three translated versions of ＂Gui Yuan＂ provides various methods dealing with this problem. Through a comparative analysis, the relativity of untranslatability is confirmed, and the relations between linguistic and cuhural untranslatability based Catford＇s theory are further explored. Besides, the limitation of Catford＇s prediction is pointed out.