Modern Mandarin has a special structure with a adjective modified by a numeral yi(=one) and a temporary classifier indicating body part. We have the reasons like below to believe that the structure has already become a much more conventionalized construction with its unique meaning compared with that of Ming or Qing dynasty.First, the construction ‘yi+classifier+adjective’ has adjective heads with high frequency unlike before. Second, it is used mainly as a predicate not as a subject or a object. Third, it can not have additional intensifier before its adjective head. Forth, it is making expansion of its usage with more kinds of classifier and adjective.The whole construction ‘yi+classifier+adjective’ is not considered as nominal phrase with nominalize head but adjective phrase because the head within the construction is not nominalized like before any more, but maintains its function of a adjective, and the ‘yi+classifier’ within the construction is analyzed as a adverbial phrase modifying the adjective.