Onomatopoeias in both Persian and Kurdish, despite having common features, are fundamentally different in terms of classification and PHONETIC STRUCTURE. These kinds of words in Persian are considered as nouns; while in Kurdish, because in addition to nominal onomatopoeias, there are also verbal onomatopoeias, such words are practically divided into two categories: noun and verb. In terms of PHONETIC STRUCTURE, onomatopoeias, as a special lexical family, in each of these two languages often have specific patterns that do not exist in other words. The pattern of syllable sequences and Phoneme combinations in onomatopoeias differs from non- onomatopoeias words and the combination of consonants in this type of word do not face the limitations that exist in other words. Patterns of PHONETIC STRUCTURE of onomatopoeias in Persian language are often based on the process of repetition, whether repetition in syllable or repetition in phoneme; for this reason, music and rhythm harmony are a prominent feature in the STRUCTURE of the onomatopoeias of this language. In contrast, in Kurdish onomatopoeias, there is no repetition in phonemes and syllables, and the PHONETIC STRUCTURE of these words is not based on a specific process and only in the case of the infinitive, they all end in the vowel "e".