Language is a hierarchical system,and units at different levels have different functions and properties.Language units are an important part of the language system and the basis of studying the grammar.In different languages,the criteria for determining language units and the naming of language units are different.By refining the representative views and new views on the division of language units in linguistic researches,we can confirm the division of language units from the whole(general linguistics)and part perspective(taking Chinese and Russian for examples),which is helpful to the theoretical research of language and language teaching.