Word formation is one of the basic means for richness of lexical composition of a language. What organize the new words are not only the root connectors but also connection of affixes to roots. According to scholars, the organization of words in Tajik language through affixes has a long history. One of the suffixes which has a major role in word formation is (iای). This suffix is attributed to the group of omomorphema and plays a role in noun formation (Niki, (wellness), Doshmani, (enmity), khoubi (goodness)), adjective formation (Madari (motherhood), Sanjeshi (Measurement)) and word formation and combination of words. Another role of the mentioned suffix is the compounding of the words. Scholars from the second half of the 20^th century have taught the words compounding principle and many researchers have expressed their ideas on word compounding. The author of this study has tried  as far as possible to discuss the scholars' ideas on compounding principle  of  word formation and about the Bidel's verses  demonstrate that the  above mentioned word formation is one of the methods of enriching the literary language of old and current  Tajik language. In particular, in word formation, the role of (iای ) and (a ا ) suffixes have been investigated. The models of mixed word formation were different, and they were investigated in Bidel's verses.