Daur language contains a group of Mongolian ancient words with ancient meanings. Due to indifferent property of language development and evolution, there have been emerged different directions such as the intellectual content, thinking content and coordinating content. As a result of this, there have also been occured phenomena including expansion of word meaning, content distortion, change in semantics etc, especially correspondence with similar meaning, synonym correspondence, or non correspondence in semantics etc. Especially, if to compare with Mongolian language of the Middle Ages, the similar coincidence in word semantics was considered to be significantly important. Evolution and development of Daur language has been conducted relatively slowly in comparison with the same process of Mongolian language. Such difference in language development process and evolution is primarily associated with occurrence of conflicts or non-similarity between languages within of Mongolian language groups. Difference between languages serves as the basis for language studies. If there is no difference, then there will be no any comparison, if there is no comparative studies, then there will be no any possibility to identify language development law and principles. Different features and properties between Mongolian and Daur languages can serve as the main ground and evidence for identification of features and concepts of our linguistic development and language evolution.