The goal of this research is investigation of simple verbs root in Persian Language which coronal nasal [n] is their coda. We are going to see, which kind of constraints are acted on the nasal [n] in final cluster of C
0VC
1C
2 as the first member. In other words, in simple verbs root that [n] is coda, after adding past affix, which kind of constraints are acted on final cluster? To this end, among 397 simple verbs root, without repeat and without causative affix, 22 monosyllabic, bi syllabic and tri syllabic verbs root that their final syllable was CVn+d were investigated. The resulted constraints are: 1) the clusters which their C
1 is [n] never formed with one of the cores of [u, i]; in other words, high vowels cannot be the core of a syllable by final cluster [nd]. 2) Nasal [n] doesn’t change at the end of monosyllabic roots by mid and low cores; in other words, [-high] vowels can be the core of a syllable by final cluster [nd]. 3) Blocking rule prevents producing of the existing similar outputs in a language. 4) The sonority sequencing principle (SSP) is considered in all past stem forms of verbs.