This paper deals with co-compositional morphemes in Taiwanese Southern min. the notion of co-compositional morphemes owes much of its insight to previous works such as Isachenko (1958), Sproat & Shih (1996) and Lien (2000). We come to a better understanding of the term of co-compositional morphemes the paper mainly focuses on such issues as literary and colloquial readings, the division of labor between them, the competition between them, collocation, versatility and productivity as well as a comparison between Taiwanese Southern min and Mandarin in the use of co-compositional morphemes. The data on which the paper is based consist of written forms culled from dictionaries and spoken forms based on a linguistic survey of 100 subjects which show real sound values and changes of co-compositional morphemes in Taiwanese Southern Min.