There are two essential meanings of the word ‘you’, one is possession, the other is existence. These are the original meanings used in various grammatical structures of which adapt the word you. The evolution of language theory is based on the variation, selection, regeneration and duplication. you is also reanalaysis and analogy. This study intended to review the diachronic and synchronic changing procedure of you. we analysed from Qin and Han Dynasties to contemporary Chinese language, to reach the following 3 conclusions. (1) essential meanings of the word you evolvement into the comparing mark, (2) essential meanings of the word you evolvement into mark of nominal elements, (3)essential meanings of the word you evolvement into the mark of the perfect aspect.