By examining the defining of the Being of Dasein by Zeitlichkeit,the mutual-defining of time and language,and the temporal relationship between Dasein and language,the paper attempts to establish that both the real wholeness of Dasein and the true nature of language as such can be achieved phenomenonally only from the approach of Zeitlichkeit(timeliness),and Dasein and language are homogeneous in terms of temporal construction.Zeitlichkeit is by nature disclosing(Ekstase),and Dasein is that which is disclosed;therefore,timeliness constitutes the being of Dasein,which in turn exists as timeliness.The Zeitigung of Ereignis gives rise to the zeigen of language,which in turn is the zeitgen of the timeliness of Being(Sein)itself.The Being of Dasein and language emerge simultaneously,with Dasein doing so by gathering itself as soon as language does the same.Both Dasein and language act on being,or act on and are relevant to each other through being,which refers to the being of timeliness in Zeitigung.Both the timeliness of Dasein and language are rooted in the Zeitigung/Ekstase.In the open zone of the temporal end of Ereignis,Dasein and language obtain access to their essence and achieve their essential things.