This paper investigates epenthesis process in Persian to catch some results in relating to vowel and consonant insertion in Persian lexicon. This survey has a close relationship to the description of epenthetic consonants and the conditions in which these consonants are used. Since no word in Persian may begin with a vowel, so that hiatus can't be considered immensely in Persian. But there are several reasons to reject such a substantial claim; as the best well-known of them is clitics, such as; plural suffix /-[alpha]n/, nominalizer/adjectivizer suffix /-i/, and also the bound morpheme "to be"/-ast/. Obviously, these morphemes begin with a vowel because of dependency on their before words, thus as a result it occurs hiatus. In order to resolve hiatus, it should be inserted an epenthetic consonant between them. With respect to the features of this epenthetic consonant, it should be said that it doesn't create any distinctive meaning and so it doesn't place in contrast with any phoneme. Since the speaker has no authority in the choice of this epenthetic consonant, thus it isn't distinctive and just has the structural function, as well as it is still inserted for the context recovery and suitable syllable structure in Persian. Furthermore, this process shows that a consonant insertion in different languages is the phonological pattern used for the world constraint recovery in phonotactics, so that it has a close relationship with syllable structure. Also, the presented study evaluates its analysis within the framework of optimality theory (Prince & Smolensky, 1993). This theory employs a notion of constraint dominance and a mechanism for selecting the optimal output with respect to a set of ranked constraints. (Contains 2 tables.)